Creamy, dense, properly peanut-buttery fudge made with four everyday ingredients and a microwave.
No stove, no candy thermometer, and the fridge does the hard part for you.
Let’s talk about fudge for a second. Old-school fudge has a bit of a reputation. Boiling sugar, candy thermometers, that nervous moment where you wonder if it’ll set or turn grainy. This peanut butter fudge skips all of that. You melt peanut butter and butter together, stir in vanilla and powdered sugar, press it into a pan, and walk away.
And what you get back is a slab of seriously smooth, melt-in-your-mouth fudge with a big, roasty peanut butter flavour and just enough sweetness. It’s soft enough to bite through easily but firm enough to stack on a plate. Little squares of this are the sort of thing that quietly disappear off a Christmas cookie tray while everyone’s busy admiring the fancier stuff.
It’s also a great one to have up your sleeve for the holidays because it’s made ahead, it keeps well in the fridge, and it freezes. Edible gifts, cookie swaps, bake sales, a sweet bite after dinner. This easy peanut butter fudge covers all of them.
Why You’ll Love This Peanut Butter Fudge
- Just 4 main ingredients: peanut butter, butter, vanilla and powdered sugar. That’s it (plus optional salt and add-ins).
- No stove, no thermometer: everything melts in the microwave, so there’s no boiling sugar to babysit.
- Super creamy texture: the powdered sugar dissolves into the peanut butter mixture for fudge that’s smooth, not grainy.
- Make-ahead friendly: it needs to chill anyway, so it’s perfect for making the day before you need it.
- Makes a big batch: one pan gives you 48 squares, which is plenty for gifting and sharing.
- Easy to customise: fold in chocolate chips, peanuts or chopped peanut butter cups to make it your own.
Ingredient Notes & Easy Substitutions
Creamy peanut butter – This is the star, and it’s also what helps the fudge set. Use regular store-bought creamy peanut butter. Natural peanut butter only works if it’s not oily at all, because that separated oil can stop the fudge from firming up properly. Crunchy peanut butter is fine if you like little bits of peanut through it. Other nut butters are a gamble here, since the recipe relies on peanut butter’s texture to set, so treat any swap as an experiment.
Unsalted butter – Adds richness and that silky, melt-in-your-mouth feel. Slice it before it goes in the bowl so it melts at the same pace as the peanut butter. Unsalted lets you control the salt yourself.
Pure vanilla extract – A small amount, but it rounds out the sweetness and makes the peanut flavour taste fuller.
Confectioners’ sugar (powdered sugar) – This is what turns the melted mixture into fudge. Sift it before you measure, and measure exactly 4 cups, because the weight can vary a bit between brands. Don’t swap in granulated sugar. It won’t dissolve the same way and you’ll end up with gritty fudge.
Salt (optional) – Just a pinch takes it into salty-sweet territory, which is very good with peanut butter. Skip it if your peanut butter is already quite salty.
Add-ins (optional) – Chocolate chips, peanuts or chopped peanut butter cups. Keep it to the amount in the recipe card so the fudge still holds together.
Step-by-Step Guide to Making Peanut Butter Fudge
1. Line your pan
Line an 8 or 9-inch square pan with foil and leave some hanging over the sides. Those overhangs are your handles for lifting the whole block out later, which makes cutting neat squares so much easier.
2. Melt the peanut butter and butter
Put the peanut butter and sliced butter in a large bowl and microwave, stopping to stir every minute. Keep going until it’s completely melted and smooth, with no streaks of butter left. Stirring each minute is what keeps it even and stops any spots from overheating.
3. Stir in the vanilla (and salt)
Take the bowl out and stir in the vanilla, plus the salt if you’re using it. A big silicone spatula or wooden spoon is your friend here, because things are about to get thick.
4. Add the powdered sugar
Tip in the sifted powdered sugar and stir until there are no dry pockets left. Don’t panic when it gets really, really thick. It’s supposed to look and feel a lot like cookie dough. If you’re adding chocolate chips, peanuts or peanut butter cups, fold them in now while the mixture is still warm.
5. Press, cover and chill
Press the fudge into the pan and smooth the top with the back of a spatula or spoon. The surface will look a little oily, and that’s completely normal. Cover the pan tightly with foil and chill for at least 4 hours, until firm. Then lift it out with the foil and cut it into squares.
Easy Peanut Butter Fudge
Equipment
- 8-inch or 9-inch square baking pan
- Aluminum foil
- Large microwave-safe bowl
- Large silicone spatula or wooden spoon
Ingredients
- 1 cup creamy peanut butter 250g, see Note 1
- 1 cup unsalted butter 2 sticks or 230g, sliced
- 1 teaspoon pure vanilla extract
- 4 cups confectioners' sugar 460g, sifted before measuring, see Note 2
- 1/4 teaspoon salt optional
- 3/4 cup add-ins optional: chocolate chips, peanuts or chopped peanut butter cups
Instructions
- Line the pan with foil, letting it hang over the sides so you can lift the fudge out once it has set.
- Add the peanut butter and sliced butter to a large bowl. Microwave, pausing every minute to give it a stir, until everything is melted and smooth.
- Remove the bowl and stir in the vanilla using a large silicone spatula or wooden spoon. Stir in the salt now if you want a salty-sweet fudge.
- Add the sifted confectioners' sugar and stir until no dry sugar remains. The mixture will be very stiff, much like cookie dough. Fold in any add-ins while it is still warm.
- Press the mixture into the lined pan and smooth the surface with the back of a spatula or spoon. It is normal for the top to look slightly oily.
- Cover the pan tightly with foil and refrigerate for at least 4 hours, until firm. Lift out using the foil and cut into 48 squares.
- Keep in an airtight container in the fridge for up to 1 week.
Notes
- Peanut butter: Go for regular store-bought creamy peanut butter rather than homemade. Natural peanut butter is fine only if it is not oily at all. Crunchy peanut butter works too.
- Confectioners' sugar: Sift it first, then measure. Brands vary in weight, so measure exactly 4 cups.
- To freeze: Freeze for up to 2 months. Thaw in the fridge for 2 to 4 hours.
- Nutrition: Estimated per square, without the optional salt and add-ins.
Nutrition
Tips for the Best Peanut Butter Fudge
- Sift, then measure: sifting first gives you the right amount of sugar and gets rid of lumps that won’t stir out of thick fudge.
- Slice the butter: smaller pieces melt evenly alongside the peanut butter, so you’re not over-heating one while waiting on the other.
- Stir every minute: short bursts with a stir in between give you a smooth, glossy base for the sugar.
- Use a sturdy spoon: a whisk will just clog up. A large silicone spatula or wooden spoon handles the thick mixture best.
- Give it the full chill: 4 hours is the minimum. Cutting too early gives you soft, squishy edges.
- Cover it tightly: a tight layer of foil keeps the fudge from picking up fridge smells or drying out.
Common Mistakes to Avoid
- Using oily natural peanut butter: the loose oil can stop the fudge from setting. Stick with regular creamy peanut butter, or a natural one that isn’t oily at all.
- Skipping the sifting: lumps of powdered sugar stay as lumps. Sift before you measure.
- Swapping in granulated sugar: it won’t dissolve into the mixture, so the fudge turns gritty. Powdered sugar only.
- Adding mix-ins once it’s cooled: the fudge stiffens as it cools, making add-ins hard to fold through. Add them while it’s still warm.
- Cutting it too soon: if it’s not fully firm, the squares will slump. Wait the full 4 hours, or longer.
- Forgetting the foil overhang: without it, getting the fudge out in one piece is a fight. Leave plenty of foil over the sides.
Easy Ways to Change It Up
The recipe card is the classic version. These are optional twists:
- Chocolate chip peanut butter fudge: fold chocolate chips through the warm fudge for a chocolate and peanut butter combo.
- Peanut butter cup fudge: chopped peanut butter cups make it extra indulgent.
- Nutty crunch: use crunchy peanut butter, or fold in peanuts for more texture.
- Salty-sweet: add the optional salt to the mixture for a more grown-up flavour.
- Holiday gift boxes: cut smaller squares and pack them in tins or boxes lined with baking paper.
How to Serve Peanut Butter Fudge
Serve it straight from the fridge, cut into small squares. It’s rich, so a little goes a long way. Pile it onto a Christmas dessert board with cookies and other candy, add it to cookie-swap boxes, or set out a plate with coffee after dinner. A glass of cold milk alongside is hard to beat, too.
Make-Ahead and Storage Tips
- Make ahead: this fudge needs at least 4 hours in the fridge, so making it the day before is ideal.
- Fridge: keep it in an airtight container in the refrigerator for up to 1 week.
- Freezer: freeze for up to 2 months.
- Thawing: move it to the fridge and let it thaw for 2 to 4 hours before serving.
- Keeping it neat: store the squares in a single layer, or separate the layers with baking paper so they don’t stick together.
Frequently Asked Questions
Why didn’t my peanut butter fudge set?
The most common reasons are oily natural peanut butter, not enough powdered sugar, or not chilling it long enough. Use regular creamy peanut butter, measure the sifted sugar carefully, and give it at least 4 hours in the fridge.
Can I use natural peanut butter?
Only if it isn’t oily at all. Separated oil can stop the fudge from firming up, so regular store-bought creamy peanut butter is the safer choice.
Can I use crunchy peanut butter?
Yes. Crunchy peanut butter works and gives you little bits of peanut through every square. Just make sure it’s a regular, non-oily one.
Why is my fudge grainy?
Usually it’s lumpy or un-sifted powdered sugar, or granulated sugar used by mistake. Sift the powdered sugar before measuring and stir until it’s completely combined.
How long does peanut butter fudge last?
Up to 1 week in an airtight container in the fridge, or up to 2 months in the freezer. Thaw frozen fudge in the fridge for 2 to 4 hours.
If you’ve been put off making fudge by candy thermometers and boiling sugar, this is the one to start with. It’s smooth, rich and packed with peanut butter flavour, and the hardest part is waiting for it to chill.
Make a pan for the holidays, keep a few squares for yourself, and box up the rest. Little gifts of homemade peanut butter fudge never seem to go to waste.
