Step 1

Preheat oven to 350 degrees F (175 degrees C). Grease a 9x9-inch baking pan.

Step 2

Beat sugar and butter together in a bowl using an electric mixer until smooth and creamy; beat in yogurt until smooth. Stir vanilla extract into mixture.

Step 3

Mix flour and baking powder together in a separate bowl. Stir flour mixture into butter mixture; add lemonade mix and stir. Stir milk into batter until smooth; pour into the prepared pan.

Step 4

Bake in the preheated oven until a toothpick inserted in the center comes out clean, 30 to 40 minutes. Cool for 10 to 20 minutes before slicing.