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.
Spoon batter into prepared muffin cups, filling them about 2/3 full.
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.
Cool cupcakes in the pans for 5 minutes; transfer cupcakes to cooling rack to finish cooling.
Place raspberries, 1 tablespoon water, and white sugar in a blender and pulse several times to chop raspberries; blend until pureed, about 30 seconds.
Whisk cornstarch with 1/4 cup water until thoroughly combined; pour mixture into the raspberry mixture in the blender and blend again until smooth.
Pour raspberry mixture into a saucepan and simmer over low heat until thickened, about 5 minutes. Let the raspberry filling cool.
Cut a core out of each cupcake about 1 1/2 inches long and 1 inch in diameter.
Spoon about 2 teaspoons raspberry filling into each cupcake.
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.
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.
Slowly beat in remaining confectioners’ sugar until smooth; if frosting is too stiff, beat in more milk, 1 teaspoon at a time.
Spread or pipe the white chocolate frosting over the cupcakes to cover the raspberry filling; drizzle or pipe any remaining raspberry filling over cupcakes. If using a piping bag and decorative tip to ice the cupcakes, make sure that the white chocolate is completely melted and there are no small chunks.
Preheat an oven to 350 F (175 C). Line a standard muffin tin with paper cupcake liners.
Beat the cake mix, water, vegetable oil, and egg whites together on low speed for 30 seconds, then on medium for 2 minutes, until smooth. Fill cupcake liners 1/3 full with white batter; set aside.
Stir 4 drops of red food coloring into the remaining bowl of batter to make the batter pink, stir in the raspberry oil. Pour 1/3 of pink batter into a resealable plastic bag and set aside.
Mix more food coloring into the remaining bowl of pink batter until it is an orange/red color and pour the batter into a resealable plastic bag. Cut a corner off the bag, stick the open tip into the center of each cup of white batter and squeeze in about two tablespoons of red batter.
Cut the corner off the bag with the pink batter, stick the open tip into the center of the red batter and squeeze about 1 tablespoon pink batter into each cup.
Bake the layered cupcakes in the preheated oven until a toothpick inserted into the center comes out clean, 15 to 20 minutes. Cool completely before frosting.
Preheat oven to 350 degrees F (175 degrees C). Grease two 12 cup muffin pans or line with 20 paper baking cups.
In a large bowl, beat the butter and sugar with an electric mixer until light and fluffy. Mix in the eggs, buttermilk, red food coloring and vanilla. Stir in the baking soda and vinegar. Combine the flour, cocoa powder and salt; stir into the batter just until blended. Spoon the batter into the prepared cups, dividing evenly.
Bake in the preheated oven until the tops spring back when lightly pressed, 20 to 25 minutes. Cool in the pan set over a wire rack. When cool, arrange the cupcakes on a serving platter and frost with desired frosting.