Preheat oven to 350 degrees F (175 degrees C). Line two 12-cup muffin tins with paper liners.
Beat 1 cup butter and 2 cups white sugar together in a bowl using an electric mixer until creamy and smooth. Beat in eggs, one at a time, until just incorporated. Stir in raspberry extract. Gradually stir flour, alternating with milk, into creamed butter mixture until just combined; stir in 6 drops food coloring. Pour batter into prepared muffin cups, filling them 3/4 full.
Bake in the preheated oven until a toothpick inserted in the center of a cupcake comes out clean, about 20 minutes. Cool in the pans for 10 minutes before removing to cool completely on a wire rack.
Place blueberries, 1/4 cup white sugar, and cornstarch in a saucepan; bring to a boil. Cook, stirring constantly, until thickened, 3 to 5 minutes. Remove from heat and allow to cool to room temperature.
Cut a small hole in the top center of each cupcake. Pipe the blueberry filling mixture into the holes.
Place 1/2 cup butter in a bowl; beat confectioners' sugar, 1/2 cup at a time, into butter using an electric mixer until just combined. Beat in strawberry extract, vanilla extract, and cream. Gently stir about 4 drops blue food coloring into frosting only until a blue-white effect is created. Pipe the frosting on top of each cupcake.
Cut the candies to look like a shark's fin. Place one fin on top of each cupcake.