PButtery shortbread, creamy peanut butter filling and chocolate on top make these peanut butter shortbread bars impossible to resist. They’re like a peanut butter cup with a layer of cookie on the bottom.
These peanut butter shortbread bars are very similar to millionaire’s shortbread (or a caramel slice if you’re Aussie) – only instead of a layer of thick caramel in the middle, there’s creamy peanut butter filling. You have the standard shortbread on the bottom and milk chocolate on top. But the middle is really where the magic happens. It’s creamy, sweetened peanut butter that tastes like the middle of a peanut butter cup.
The recipe itself is quite easy, but because of the 3 layers, there are quite a few steps. Don’t worry – a novice baker can make these perfectly.
3-Layer Peanut Butter Shortbread Bars
The base is an easy, buttery shortbread made with only a few ingredients: butter, sugar, flour, cornstarch and a pinch of salt. I like to add in a little cornstarch because it makes the shortbread softer – but if you’re in a pinch, you could substitute it for 1 extra tablespoon of flour. The shortbread isn’t overly sweet, which is exactly the way it should be. Buttery, tender and a little crunchy too. You’ll press the dough into the bottom of a lined 8×8 inch (20×20 cm) pan – then it goes in the oven to bake for 22-25 minutes.
After the base is baked and cooled – it’s time for the peanut butter center. It’s very similar to the base layer of my favorite no-bake peanut butter bars and tastes like the middle of a peanut butter cup. It’s a thick peanut butter filling that’s sweetened, but definitely not as sweet as a peanut butter frosting. It gets spread over top of the shortbread base, and then pop it in the fridge as you make the chocolate topping.
The chocolate topping is simply melted chocolate with a little butter to help it slice more easily. I like to use 4 oz milk chocolate (112 grams) and 2 oz dark chocolate (56 grams) – but you can really use whatever type of chocolate you prefer. Milk, dark, semi-sweet – you do you. When melting chocolate, it’s super important that your microwave is on medium power and not high power (which is often the default on many models). High power can bake or even burn the chocolate, causing it to go lumpy or grainy. Then pour the chocolate over top of the peanut butter layer, and pop the pan in the fridge to harden.
Pro Tip: When the chocolate is about 75% hardened, score the top of the bars with a thin, sharp knife through the chocolate layer where you plan to cut the bars. This makes it super easy to slice the bars after they’ve fully hardened without the chocolate cracking.
These peanut butter shortbread bars are rich without being overly sweet, and taste like a delicious peanut butter cup on top of a buttery shortbread cookie. Delicious, easy to make, and perfect if you love a good peanut butter dessert.
If you love peanut butter cups – then I’d definitely try:
Peanut Butter Shortbread Bars
- 8x8 inch (20x20 cm) baking pan
- ⅔ cup unsalted butter softened
- ⅓ cup caster sugar aka white sugar
- 1 ⅓ cup all-purpose flour aka plain flour
- 1 tablespoon cornstarch
Peanut Butter Layer
- 3 tablespoons unsalted butter softened
- 1 cup smooth peanut butter*
- 1 teaspoon vanilla extract
- 1 ⅓ cup powdered sugar
- 6 oz chocolate* I typically use 4 oz milk chocolate and 2 oz dark chocolate
- 1 tablespoon unsalted butter
- Preheat the oven to 325F degrees and line an 8x8 inch (20x20 cm) pan with parchment paper, leaving an overhang around the edges. Or line with aluminum foil and lightly grease.
- In a medium bowl, beat together the butter and sugar until combined.
- Carefully mix in the flour and cornstarch, only mixing until just combined.
- Press the mixture into the bottom of the lined pan to form an even layer.
- Bake in the preheated oven for 22-25 minutes or until the top looks completely set. The edges may just be starting to brown.
- Remove from the oven (keeping the bars in the pan) and cool fully (usually at least 1 hour).
Peanut Butter Layer
- In a medium bowl, beat together the butter and peanut butter.
- Add in the vanilla extract and powdered sugar. Beat the mixture together starting with the mixer on low speed. It should be thick and almost a little dry feeling when you're done.
- Press the peanut butter mixture on top of the cooled shortbread base and spread the top flat.
- Pop the bars in the fridge as you make the chocolate topping.
- Chop the chocolate into very small pieces and place in a heatproof bowl with the butter chopped into a few small pieces.
- Microwave on medium power (do not microwave on high or standard power, or the chocolate can get grainy). for 45 seconds. Remove from the microwave and stir. Repeat the process until the chocolate is smooth.
- Pour the chocolate on top of the peanut butter layer and smooth the top.
- Return the bars to the fridge for the chocolate to harden.
Slicing & Serving
- When the chocolate on top is about 75% hardened (it will look slightly glossy, but no longer wet) gently score the top of the bars with a thin, sharp knife (such as a paring knife) where you plan to slice the bars. Return to the fridge to continue hardening.
- Once the chocolate is set, lift the bars out of the pan using the overhang of the parchment paper and place on a cutting board. Slice the bars with a sharp knife (not a table knife), and serve.
- Make sure to use smooth, stabilized peanut butter. Do not use natural, whipped or homemade peanut butter because it can separate and leak oil. Peanut butter such as Skippy, Jiff or Kraft work perfectly.
- Feel free to use your favorite kind of chocolate - milk, dark or semi-sweet work perfectly. 6 oz of chocolate is equal to 1 cup of chocolate chips. I prefer to use chopped chocolate because it melts more easily than chocolate chips and is less likely to become grainy - but chocolate chips work too.
- This recipe can be doubled and made in a 9x13 inch pan. The bars will be a little thicker if using a 9x13 inch pan, and the bake time for the shortbread layer will be closer to 25-30 minutes.
- Store bars in an airtight container at room temperature for up to 4 days, or in the fridge for up to 1 week. If your kitchen is particularly warm, you may want to store them in the fridge.
- Nutrition information is an estimate only and is based on 1 slice, assuming the pan is cut into 9 equal slices.