
Place butter in a medium-sized mixing bowl and use an electric mixer to beat until it is smooth and creamy.
Gradually add sugar, stirring on low speed until fully incorporated.
Add vanilla extract and salt and stir to combine. Use a spatula to scrape the bottom and sides of the bowl and stir again.
Line a baking tray or large plate with wax paper. Scoop filling by 2 teaspoon-sized scoops (11g) and drop onto prepared tray. Place in freezer while you prepare your dough (filling must chill for a minimum of 20 minutes).
In a large mixing bowl, use an electric mixer to beat butter and sugar together very well, until light and fluffy.
Add eggs and vanilla extract and beat together again to thoroughly combine.
In a separate, medium-sized mixing bowl, whisk together flour, black cocoa, baking powder, and salt.
Gradually add dry ingredients into wet (I do this in 3 or 4 parts), stirring after each addition until ingredients are thoroughly combined.
Scoop cookie dough by 3 Tablespoon-sized scoop (64g) and roll gently between your palms. Use your thumb to press an indent all the way into the center and press one frozen filling dollop into the center. Use the cookie dough to completely conceal the filling, and roll gently between your palms to create a smooth, even ball of dough. Place in freezer to chill for 30 minutes.
Preheat oven to 375F (190C) and line baking sheets with parchment paper.
When the dough has finished chilling, remove from freezer and place on prepared baking sheets, spacing cookies at least 2” apart. Bake in preheated 375F (190C) oven for 11-12 minutes. Allow cookies to cool completely on baking sheet before enjoying!