Step 1

Line a 6 x 8 (or similar sized) glass pan with plastic wrap or wax paper misted very lightly with cooking spray. Set aside.

Step 2

Place powdered sugar, cocoa powder, cubed butter, and milk into a large bowl.

Step 3

Microwave for 90 seconds.

Step 4

Whisk until smooth.

Step 5

Whisk in vanilla and optional nuts.

Step 6

Pour into prepared pan, cover, and chill in the refrigerator until set.