Preheat the oven to 350°F (175°C) and grease and flour two 9-inch round cake pans.
In a large bowl, use an electric mixer to beat the sugar, butter, and Jell-O® until light and fluffy.
Add the eggs one at a time, beating well after each addition.
In a separate large bowl, combine the flour and baking powder.
Alternately stir the flour mixture and milk into the butter mixture.
Mix in the strawberry puree and vanilla.
Divide the batter evenly between the prepared pans.
Bake for 25 to 30 minutes, or until a toothpick inserted into the center comes out clean.
Cool the cakes on a wire rack for 10 minutes and then carefully invert onto a serving plate or cooling rack to cool completely.