In a stand mixer beat the butter until fluffy. Stir in white sugar and beat until well combined. Then add the vanilla and egg. Mix well.
In a bowl mix the flour, baking soda and cocoa powder and add it to the butter mixture beating until is well incorporated and finally stir in the reese’s peanut butter and white chocolate chips.
In a baking tray lined with wax paper or aluminum foil place small balls of dough with enough space for them to grow you can use a medium ice scoop.
Bake for 8-10 minutes. It’s better not over baking them since you want them chewy!