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Galaxy Glow Cake - Make a black or navy cake with swirls of UV-reactive food coloring in purples, blues, and pinks to create a glowing galaxy effect.

Galaxy Glow Cake

This Galaxy Glow Cake is a mesmerizing dessert featuring a deep black or navy cake with vibrant UV-reactive swirls of purple, blue, and pink frosting. Under a blacklight, the colors glow, creating a stunning cosmic effect perfect for space-themed celebrations!
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Prep Time 40 minutes
Cook Time 30 minutes
Total Time 1 hour 10 minutes
Course Dessert
Cuisine American
Servings 12 slices
Calories 480 kcal

Equipment

Ingredients
  

  • 2 1/2 cups all-purpose flour
  • 3/4 cup unsweetened black cocoa powder for deep color
  • 2 tsp baking soda
  • 1 tsp baking powder
  • 1/2 tsp salt
  • 1 cup unsalted butter softened
  • 1 3/4 cups granulated sugar
  • 3 large eggs
  • 1 tbsp vanilla extract
  • 1 cup buttermilk
  • 1/2 cup hot coffee enhances chocolate flavor
  • 3 cups buttercream frosting divided
  • 1 tbsp black gel food coloring for deep night sky base
  • 1 cup tonic water for UV-reactive glow effect
  • 1/4 tsp vitamin B2 powder optional, enhances UV glow
  • 3 drops neon pink gel food coloring
  • 3 drops neon blue gel food coloring
  • 3 drops neon purple gel food coloring
  • 1 tsp edible silver or white food paint for stars and highlights

Instructions
 

  • Preheat the oven to 350°F (175°C) and grease two 8-inch cake pans.
  • In a mixing bowl, whisk together the flour, black cocoa powder, baking soda, baking powder, and salt. Set aside.
  • In another bowl, beat the butter and sugar with an electric mixer until light and fluffy.
  • Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.
  • Gradually add the dry ingredients, alternating with buttermilk and hot coffee, mixing until just combined.
  • Divide the batter evenly between the prepared cake pans and smooth the tops.
  • Bake for 28-30 minutes, or until a toothpick inserted into the center comes out clean.
  • Let the cakes cool in the pans for 10 minutes, then transfer to a cooling rack to cool completely.
  • Tint half of the buttercream frosting black using the black gel food coloring and set aside.
  • For the glowing galaxy swirls, mix the tonic water with the remaining buttercream and divide into three bowls.
  • Tint each bowl with neon pink, neon blue, and neon purple food coloring.
  • Frost the entire cake with the black buttercream for a deep space background.
  • Using a piping bag or offset spatula, randomly swirl the neon-colored frostings over the black base and gently blend for a galaxy effect.
  • Dip a clean paintbrush into the edible silver or white food paint and flick tiny specks across the cake to resemble stars.
  • Chill the cake for 30 minutes before serving. Display under a blacklight to reveal the glowing galaxy effect!

Notes

  • Storage: Store in the refrigerator for up to 5 days. Bring to room temperature before serving.
  • UV Effect: Tonic water and vitamin B2 enhance the glow under blacklight. The stronger the UV light, the brighter the effect.
  • Extra Decoration: Add edible glitter or neon-colored sprinkles for an even more cosmic look.

Nutrition

Serving: 1sliceCalories: 480kcalCarbohydrates: 65gProtein: 5gFat: 22gSaturated Fat: 14gPolyunsaturated Fat: 1gMonounsaturated Fat: 5gCholesterol: 90mgSodium: 260mgPotassium: 120mgFiber: 3gSugar: 50gVitamin A: 600IUCalcium: 80mgIron: 2mg
Keyword Blacklight Cake, Cosmic Cake, Galaxy Glow Cake, Glowing Cake, Space-Themed Dessert
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