When the cupcakes come out of the oven, be prepared for a sweet strawberry smell that will fill up your kitchen and attract family from other rooms.
Whisk together flour and baking powder; set aside. In a separate bowl, cream sugar, butter and gelatin. Add eggs and beat well. Alternate adding flour mixture and milk to the creamed mixture. Add vanilla and puréed strawberries.
Pour batter into prepared muffin pans. Bake at 350° F for 15-20 minutes or until the center tests done. Cool on a rack for 30 minutes before piping in filling and topping with frosting. Garnish with a sliced strawberry, if desired.