Cupcakes:

1 box vanilla cake mix (I used Pillsbury Traditional Vanilla)
1 (3 oz.) package strawberry gelatin
1 cup butter, melted
½ cup fresh or frozen strawberries, finely chopped
½ cup milk
4 large eggs

Strawberry Buttercream Frosting:

1 cup butter, softened
4 cups powered sugar, SIFTED
¼ teaspoon salt
2 tablespoon strawberry extract
2 tablespoons milk
¼ cup strawberries, finely chopped (optional)
strawberries, sliced for topping
sprinkles