Lemonade Poke Cake

1 (18 1/4 ounce) box lemon cake mix
6 ounces frozen lemonade concentrate, thawed
3/4 cup powdered sugar or to taste

prepare cake mix in 13x9-inch pan according to package directions.
Let cool slightly.

Using the handle of a wooden spoon, poke holes in cake at about 1-inch intervals. Mix lemonade concentrate and powdered sugar. If desired, microwave mixture briefly to help sugar dissolve.

Drizzle lemonade mixture evenly over the cake. Refrigerate until cold.
Spread whipped toping over cake.