Preheat the oven to 350 degrees F (175 degrees C). Grease and flour two 9-inch round cake pans.
Beat sugar, butter, and dry strawberry gelatin together in a large bowl with an electric mixer until light and fluffy. Add eggs one at a time, beating well after each addition.
Combine flour and baking powder in a large bowl; stir into butter mixture alternately with milk.
Blend in strawberry puree and vanilla.
Divide batter evenly between the prepared pans.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 25 to 30 minutes. Cool cakes on a wire rack for 10 minutes; run a table knife around the edges to loosen. Invert carefully onto a serving plate or cooling rack to cool completely.
