Preheat the oven to 350 degrees. Spray the bundt pan with cooking spray and set aside. Using a stand mixer, combine the cake mixes, eggs, butter and milk and mix on medium speed until fully combined, about 5 minutes.
Using a spoon, scoop a spoonful of each color into the bundt pan, alternating between colors.
Cool completely in the bundt pan. Once cooled, place a serving plate on the top of the bundt pan and flip the pan over so that the cake can come out onto the plate.
To make glaze - Combine all ingredients in a large bowl and mix until smooth. Pour the glaze into a measuring cup and pour the glaze evenly onto the cake. Sprinkle some patriotic sprinkles onto the glaze and let the glaze harden before serving.