1) Mix Nutella and powdered sugar in a small bowl. Then form 18 Teaspoon-sized balls of Nutella and store them on a baking sheet lined with wax paper.
2) Either in the microwave or in a double boiler, melt chocolate and milk together and set aside for later. If you use the microwave, be careful not to burn the chocolate. Let chocolate cool a bit.
3) In a stand mixer or in a bowl with a hand mixer, cream together butter and sugar until light and fluffy. Mix for a few minutes.
4) Add egg, vanilla extract, and melted chocolate mixture to dough.
5) Next add all the dry ingredients and mix to combine. Try not to over-mix the dough.
6) Chill dough for 30 minutes.
7) Scoop out a large tablespoon-sized ball of dough and roll it around a Nutella ball. Make sure Nutella is completely covered by cookie dough.
8) Dunk dough ball in peanuts and then place on a baking sheet lined with parchment paper or silicon baking sheet.
9) Once all the cookies are formed, use a measuring cup (or your hands) to smash down each ball of dough until it’s flat.
10) Bake cookies at 350 degrees F for 12 minutes. Let cool before eating.