Preheat oven to 350°F. Lightly grease baking sheet and set aside.

In a large bowl, cream butter and peanut butter together.

Whip in sugars until light and fluffy. (2 minutes)

Stir in melted chocolate, eggs, and vanilla. Scrape sides of bowl and mix again.

Slowly stir in all dry ingredients until just incorporated.

Scrape side of bowl and mix again briefly.

Stir Reese's Pieces in by hand.

Scoop cookie dough out into rounds and place onto baking sheet. Flatten slightly.

Bake for 8-9 minutes or until cookie look matte.

Cool on baking sheet 3 minutes.