Cookies & Cream Brownies: 2 cups powdered sugar, 4 Tbsp. butter, room temperature, 1 Tbsp. heavy cream, plus a little extra., approx. 8 oreos, crushed well. Combine all frosting ingredients, except the oreos and beat with a hand mixer until light and fluffy. You may need to add a bit more heavy cream to get a spreadable consistency. Mix in crushed oreos (more or less). Spread frosting evenly over cooled brownies. You can fancy these up by topping each bar with an oreo cookie half.