In a large mixing bowl, add the softened butter, peanut butter, brown sugar, granulated sugar, vanilla extract, and kosher salt. Mix with an electric hand mixer until well combined and creamy.
Add the egg and mix until the mixture is smooth.
Add the flour and mix the dough until it is just combined and there are no lumps of flour visible.
Using a cookie scoop, scoop out about 1 tablespoon of the cookie dough and roll it into balls. Using your thumb or a teaspoon, make indents on each ball.
Fill each indent with ½ teaspoon of jam of your choice, I used strawberry jam for this.
Bake the cookies in a 180c (350f) preheated oven for 10-12 minutes. Don't overbake these cookies so they will stay soft!
Notes
Use room temperature ingredients. It is important that you use room-temperature ingredients like eggs and butter. This step ensures that your mixture mixes into a homogenous mixture and bakes perfectly. you don’t want to place cold batter into the oven.
Don’t overmix the batter, you don’t want to develop the gluten in the flour. This step ensures you have moist cookies and not dense and dry cookies.
Make sure that your butter is at room temperature. An hour or two before making these cookies, take the butter out of the fridge and let it come to room temperature. The butter should be soft to the touch. If your butter is too cold, it will be harder to mix and there will be lumps of butter in the dough.
Measure your flour correctly!When measuring your flour, avoid scooping it with a measuring cup. Instead, stir the flour with a spoon to create as many air pockets as possible, and spoon it into your measuring cup. Finally, level it with a back of a knife.
Line your sheet pan with parchment paper or a silicone mat! This step helps the cookies to bake evenly, and it makes sure that your cookies release easily from the pan.
I suggest letting these cookies cool for 5 minutes and then transferring them to a wire rack to cool for at least 10 more minutes. This step ensures that the bottom of your cookies will not be soggy from the steam.