Preheat oven to 350 degrees and line a cookie sheet with parchment paper.
In a large bowl, mix the 3/4 C peanut butter and 3/4 C powder sugar together until fully combined.
Using a teaspoon, spoon out 1 tsp of the filling and roll into a ball.
Place the filling balls onto a plate and place into the fridge for 10 minutes.
In a medium bowl, combine the flour, cocoa powder, baking soda and salt.
Using a standing mixer, cream together the butter, sugars, peanut butter and milk until smooth and creamy.
Mix in the egg and vanilla and mix until combined.
Stir in the dry ingredients.
Using a small ice cream scoop, scoop out some dough and roll into a ball.
Place onto the cookie sheet and repeat steps with remaining dough.
Once all the dough has been rolled, lightly push your thumb into the center of the dough the make indents.
Place a peanut butter filling into the center and mold the dough back into a round ball, covering up the peanut butter filling.
Repeat step with remaining cookies.
Place 1/2 C of sugar into a bowl and roll all of the cookies into it.
Bake in the oven for 8-10 minutes.
Enjoy!