Preheat the oven to 350 degrees F. Grease a 9 x 13-inch baking dish and set aside.
Add the strawberry cake mix and Sprite to a large mixing bowl. Beat with a hand mixer for about 2 minutes, or until smooth.
Pour the batter into the prepared baking dish and spread evenly.
Bake for 25 to 30 minutes, or until a toothpick inserted into the center comes out clean.
Transfer the cake to a wire rack and allow it to cool completely before frosting.
In a large mixing bowl, beat the softened butter until smooth. Gradually add the powdered sugar, mixing until fully incorporated.
Add the strawberry extract and beat until combined. Mix in enough milk to create a smooth, spreadable frosting. If desired, add a few drops of pink food coloring.
Spread most of the frosting evenly over the cooled cake.
Transfer the remaining frosting to a piping bag fitted with a large star tip. Pipe 12 evenly spaced dollops across the cake.
Top each dollop with a strawberry half and serve.
Notes
Let the Sprite come to room temperature before mixing for the smoothest batter.
Mix only until combined. Overmixing can make the cake less fluffy.
Start checking for doneness at the 25-minute mark since soda cakes can brown quickly.
Make sure the cake is completely cool before adding the frosting.
Some strawberry extracts naturally tint the frosting pink, so add food coloring only if needed.
Pat the strawberries dry before placing them on the cake to prevent excess moisture from bleeding into the frosting.
Store covered in the refrigerator for up to 3 days.
For best results, add the fresh strawberry garnish shortly before serving.