Adapted from Sally's Baking Addiction
3/4 cup butter, at room temperature
1/2 cup sugar
1/2 cup brown sugar
1 1/2 teaspoons vanilla
3 cups flour
1/2 teaspoon salt
1 teaspoon baking soda
1 1/4 cups mini-chocolate chips
11 ounce bag York Peppermint Patties
Preheat oven to 350º. Line a 9 x 9 inch pan with non-stick foil. Set aside.
Cream butter and sugars till light and fluffy. Add eggs and vanilla and mix till combined. Stir in baking soda and salt, then add flour and mix till combined. Carefully mix in chocolate chips.
Press half of cookie dough in prepared pan. Top with unwrapped peppermint patties. Cover with the remaining cookie dough and spread with offset spatula to make top even and level.
Bake 34-38 minutes, till golden. Cool in pan, then place in refrigerator to chill for cleaner cutting.
Makes 16-25 depending on size.