Peanut Butter Chip Brownie Cupcakes

Bahan-bahan (18 porsi)

• 1 cup (2 sticks) butter
• 2 cups granulated white sugar
• 2 teaspoons vanilla extract
• 4 large eggs
• 3/4 cup unsweetened cocoa powder
• 1¾ cups all purpose flour
• 1/2 teaspoon baking powder
• 1/2 teaspoon salt
• 1 2/3 cups peanut butter chips ((10-ounce package), divided)