Preheat the oven to 350°F (175°C) and grease a mini muffin tin with cooking spray.
In a medium bowl, whisk together the all-purpose flour, baking soda, and kosher salt until well combined, then set it aside.
In the bowl of a stand mixer fitted with the paddle attachment, cream together softened unsalted butter, sugar, and light brown sugar until light and fluffy.
Beat in each egg one at a time into your creamed mixture, then add creamy peanut butter and vanilla extract; mix until smooth.
Gently add the flour mixture to your stand mixer bowl, beating just until combined.
Using a small ice cream scoop or two spoons, portion heaping tablespoons of dough into each muffin cup. Bake for 18-22 minutes until golden brown; immediately push a mini peanut butter cup into each cookie center before letting them cool.