Place peanuts in a food processor and pulse until finely chopped. Don’t overdo it – you don’t want to make peanut butter. Set aside.

In a small mixing bowl combine the flour, baking soda and salt until blended. In a medium mixing bowl, whisk together the melted butter, peanut butter, sugars, milk and egg. Add the flour mixture to the peanut butter mixture and blend using a spatula. Fold in the chopped peanuts gently, just until blended.

Using a cookie scoop or tablespoon measuring spoon, place 12 mounds on one prepared baking sheet. Make sure they are evenly spaced, not to close together. Lightly dampen your fingers and gently press the mounds to a 2 inch diameter cookie. Bake for about 12 minutes (rotate the pan halfway through baking) or until lightly browned and firm to the touch. Allow the cookies to cool for 5 minutes on the pan, then transfer to a wire rack to cool completely. Repeat using the cooled cookie sheet baking 12 at a time. (These cookies do best if you use a cold cookie sheet for each new batch. If you only have one cookie sheet, use a new piece of parchment paper placing the dough on the parchment and then all together on the cookie sheet. As with most cookies, they will spread too much if you use a hot cookie sheet.)

Place half the cookies upside down on the wire rack or clean work surface. Place 1 rounded tablespoon of the warm filling in the center of each cookie. Using a knife spread the filling until it’s almost to the edge. Then place a second cookie on top and gently press down until the filling spreads to the edge.