Raspberry White Chocolate Buttercream Cupcakes

Step 1
Preheat oven to 350 degrees F (175 degrees C).

Step 2
Grease 24 muffin cups or line with paper liners.

Step 3
Mix together vanilla cake mix, 1 cup water, vegetable oil, and eggs in a mixing bowl with an electric mixer on low speed until cake mix is moist. Raise mixer speed to medium and beat until batter is smooth, 2 minutes.

Step 4
Spoon batter into prepared muffin cups, filling them about 2/3 full.

Step 5
Bake in the preheated oven until cupcakes are very lightly browned and a toothpick inserted into the center of a cupcake comes out clean, 18 to 23 minutes.

Step 6
Cool cupcakes in the pans for 5 minutes; transfer cupcakes to cooling rack to finish cooling.

Step 7
Place raspberries, 1 tablespoon water, and white sugar in a blender and pulse several times to chop raspberries; blend until pureed, about 30 seconds.

Step 8
Whisk cornstarch with 1/4 cup water until thoroughly combined; pour mixture into the raspberry mixture in the blender and blend again until smooth.

Step 9
Pour raspberry mixture into a saucepan and simmer over low heat until thickened, about 5 minutes. Let the raspberry filling cool.

Step 10
Cut a core out of each cupcake about 1 1/2 inches long and 1 inch in diameter.

Step 11
Spoon about 2 teaspoons raspberry filling into each cupcake.

Step 12
Place white chocolate chips in a microwave-safe bowl and heat in 30-second intervals until chips begin to melt, about 1 minute. Stir and repeat, heating chips about 10 seconds at a time, until thoroughly melted. Stir until chocolate is smooth and no more lumps remain.

Step 13
Beat butter with an electric mixer on medium speed in a mixing bowl until fluffy. Beat in half the confectioners' sugar, melted white chocolate chips, and milk until mixture is smooth and creamy.

Step 14
Slowly beat in remaining confectioners' sugar until smooth; if frosting is too stiff, beat in more milk, 1 teaspoon at a time.

Step 15
Spread or pipe the white chocolate frosting over the cupcakes to cover the raspberry filling; drizzle or pipe any remaining raspberry filling over cupcakes.