Lucky Charms Cheesecake

Name: Lucky Charms Cheesecake
Ingredients: 1 cup whole milk; 8 ounces Lucky Charms® cereal (about 4 cups), plus more for decorating; 4 tablespoons unsalted butter, chopped; 5 ounces marshmallows; Two 1/4-ounce envelopes unflavored powdered gelatin; Two 8-ounce packages cream cheese, at room temperature; 1 cup confectioners' sugar; 1/2 cup sour cream; Juice of 1/2 lemon; 1 tablespoon pure vanilla extract; 6 ounces white chocolate, chopped; 6 tablespoons heavy cream; 1 drop lemon yellow gel food coloring; 1 drop sky blue gel food coloring; 1 drop deep pink gel food coloring; Whipped cream, for decorating