Cream together the butter, peanut butter and the two sugars until smooth.

Add in egg, vanilla and milk then mix until well combined.

Pour in the sifted flour along with salt and baking soda.

Mix until well blended but not over mix. The dough obtained should be very soft.

Form walnut sized balls. Cover the dough balls with plastic wrap and let chill in the refrigerator for about 1 hour or less.

Roll each ball of dough into a small disk ( with hands).

Place about 1 tsp of Nutella in the center of 1 disc and place the other disc on top.

Seal the edges with hands and smoothen the surface of the cookie dough formed.

Put each stuffed cookie dough in a bowl of granulated sugar to gently coat it in both sides.

Place the stuffed cookies in a baking sheet lined with parchment paper and bake them in a 375 ℉ preheated oven for 8 to 10 minutes or until golden.