Peanut Butter Cookie Bars

Peanut Butter Cookie Bars


Salty meets sweet in these Peanut Butter Cookie Bars. They’re gooey, chewy, crisp on the outside and packed full of dark chocolate chunks, salty peanut butter and crunchy peanuts.

peanut butter cookie bars

These peanut butter cookie bars are a variation on my browned butter chocolate chip cookie bars, which are honestly one of my favourite bakes I’ve ever made! The bars are so soft, chewy and gooey in the middle while still crisp on the outside. And the browned butter gives the most wonderful depth of flavour. This is taken to the next level with these bars, with the addition of salty peanut butter and crunchy peanuts. So so good! And super simple, without any cookie chilling time needed! Hooray!

Key Ingredients You’ll Need

  • Dark Chocolate – Pretty much every cookie recipe on the blog uses dark chocolate over milk or white. For me, the bitterness of the dark chocolate pairs so well against the sugary cookie dough. But of course, if you reallly prefer milk or white over dark, you can easily swap it out. You will just end up with an overall sweeter bake.
  • Crunchy Peanut Butter – Unless I’m adding peanut butter to a cake batter that I want to be smooth, I always choose the crunchy version for bakes! It just adds abit more texture and saltiness! Use your favourite brand here, or whatever you have in the cupboard!
  • Unsalted Roasted Peanuts – I really like the added crunch that the peanuts give to these bars, but make sure you use unsalted! They can be a little trickier to find, but regular salted peanuts will be way too salty for the bake! I used the KP brand.
traybake cookie

How to make peanut butter cookie bars

These bars are so easy to make, don’t need any chilling time and only need one baking pan! It honestly couldn’t be better. They taste sooo good on the day of baking too, with the chocolate still melty and the cookie still gooey. It’s like eating the best cookie dough ever, but with delicious pockets of salty peanut butter too!

Browning the butter

What really brings these cookie bars to the next level, is the browned butter. If you haven’t browned butter before, it essentially means to cook the butter until the milk solids begin to toast. The milk solids look like little flecks in the butter, that turn a dark brown colour and give the most delicious nutty flavour. Honestly, once you’ve added browned butter to a recipe you’ll find it hard not to add it to everyyy single recipe you make.

Now if you do that, just remember to add additional butter to all your recipes to make up for the lack of water. Part of the browning process means the water content in the butter evaporates. Most European butters have 18% water and most American butters 20%. So add the correct percentage of butter to your recipe, and you’re good to go!

peanut butter cookie batter
peanut butter cookie dough

Making the cookie dough

Now, once you have your browned butter, pour it into a large heat-proof bowl and set aside for just a few minutes. You want to use the butter whilst it’s still melted, but not piping hot. While you’ve set the butter aside, you can prep the chocolate and peanuts. I always prefer to use a block of chocolate rather than chips or chunks, as you get a more uneven smattering of chocolate in the cookie bars which adds such great texture! So get chopping up your chocolate and peanuts and once thats done you can begin the dough.

The butter and both caster sugar and light brown sugar needs to be whisked together for a few minutes until well combined. I prefer to use an electric hand-whisk for this, but you could whisk by hand too. Then the egg, egg yolk and vanilla can be whisked in. Next you want to add the peanut butter, which will thicken the mixture a little.

The next step is to add the dry ingredients – flour, baking powder, bicarb, salt. You only want to mix this until you can just no longer see any streaks of flour. If you overmix, your cookie bars might end up a bit tough!

Finally, both the chopped chocolate and peanuts can be added. And then its ready to be pressed into the baking tin! It’s easiest to do this by hand, as the dough is soft but quite thick. It also helps you to ensure the dough is even, so it bakes well.

peanut butter cookie dough

Tips & Tricks

How long should you bake a cookie bar?

The bake time in the recipe is 20 minutes, and I urge you not to go over this. These cookie bars are designed to be gooey in the middle, so you don’t want to overbake them!

Should you refrigerate cookie bars?

No! Like most bakes, these cookie bars are best kept at room temperature in an air-tight container. You want them to be soft, chewy and gooey.

Why are my cookie bars cakey?

Using too much flour can result in a cakey cookie bar, so make sure you are weighing your ingredients correctly. Also, make sure you are using block butter and not a butter spread as this can have a different water content which will result in less moisture in the bake.

peanut butter cookie bars

Honestly, I pretty much ate the entire pan to myself when I made these for the first time. They’re super gooey, chewy in the middle, crisp on the outside, salty/sweet…honestly I could go on! I really love them, and I hope you will do too!!

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peanut butter cookie bars

Peanut Butter Cookie Bars

Aimee Field
Salty meets sweet in these Peanut Butter Cookie Bars. They're gooey, chewy, crisp on the outside and packed full of dark chocolate chunks, salty peanut butter and crunchy peanuts.
Prep Time 30 minutes
Cook Time 20 minutes
Total Time 50 minutes
Course Biscuits
Cuisine British
Servings 8 Bars


  • 140 g unsalted butter
  • 200 g dark chocolate
  • 40 g unsalted peanuts
  • 110 g caster sugar
  • 110 g soft light brown sugar
  • 1 large egg
  • 1 large egg yolk
  • 1/2 tsp vanilla extract
  • 80 g crunchy peanut butter
  • 250 g plain flour
  • 1/2 tsp baking powder
  • 1/2 tsp bicarbonate of soda
  • 1/2 tsp table salt


  • Firstly, preheat the oven to 180C/160C Fan/Gas Mark 4. Then grease a 9x9inch square baking tin, and line the base and two opposite sides with baking paper, so you can easily lift the cookie bar out when baked.
  • For the browned butter: Place the butter into a small saucepan over a low-medium heat and melt stirring every now and then. Keep the melted butter on the heat as it foams, stirring every now and then until the foaming subsides and you're left with a light brown butter with darker flecks. Then take off the heat and pour into a large heat-proof bowl, then set aside.
  • For the dough: Firstly, chop the chocolate and peanuts into rough chunks and set aside. Add both sugars into the bowl with the browned melted butter, then using an electric hand-whisk, whisk on a high speed until well combined. Then add the egg, egg yolk and vanilla and whisk again until well combined. Whisk in the peanut butter, until the mixture is a little thickened. Then whisk in the flour, baking powder, bicarbonate of soda and table salt until you have a soft thick dough. Finally, mix in the chopped chocolate and peanuts.
  • Tip the cookie dough into the prepared baking tin, and using your hands flatten in the tin until even. Bake in the oven for 20 minutes until lightly golden brown, then remove from the oven and leave in the tin for 15 minutes. Finally, remove from the tin and leave to cool completely on a cooling rack. Slice into 8 bars and enjoy!


Bars keep for 3-4 days in an air-tight container. 
Keyword chocolate, cookies, dark chocolate, peanut butter

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