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Poison Apple Cake

This Poison Apple Cake is made with bright green vanilla cake layers filled with creamy purple vanilla buttercream and black mirror glaze dripping down the cake.

Course Dessert
Cuisine American
Keyword Buttercream, Cake Decorating, Cake Recipe, Halloween Cake, Poison Apple
Prep Time 1 hour
Cook Time 40 minutes
Cooling/Decorating Time 1 hour 30 minutes
Total Time 3 hours 10 minutes
Servings 1 (3 Layer) 6-inch or (2 Layer) 8-inch round cake
Author Katie


Green Foolproof Vanilla Cake

  • 1/2 cup (or 1 stick) unsalted butter, room temperature
  • 1/3 cup vegetable oil
  • 1/2 cup granulated sugar
  • 4 whole eggs
  • 1 box Vanilla Cake Mix (prefer to use Duncan Hines)
  • 2/3 cup all-purpose flour, sifted
  • 1 teaspoon salt
  • 2 teaspoons vanilla extract
  • 1 cup whole milk
  • Neon green gel food coloring

Purple Vanilla Buttercream

  • 2 cups (or 4 sticks) unsalted butter, room temperature
  • 7 cups powdered sugar, sifted
  • 1 Tablespoon vanilla extract
  • 1 teaspoon salt
  • 2 Tablespoons heavy cream
  • Electric purple gel food coloring

Black Mirror Glaze

  • 1/2 cup water
  • 3/4 ounces (or 3 packets) unflavored powdered gelatin
  • 1/2 cup light corn syrup
  • 1 1/4 cup granulated sugar
  • 2/3 cup water
  • 7 ounces (or 1/2 can) sweetened condensed milk
  • 10 ounces white chocolate chips
  • Super black gel food coloring
  • 3-4 granny smith apples
  • Parchment paper for face cutouts


Green Foolproof Vanilla Cake

  1. Preheat oven to 350 °F. Spray three 6-inch round cake pans with non-stick spray, line the bottom of each pan with parchment paper and spray again. Set aside.

  2. In a medium-size bowl, whisk and stir together the cake mix, all-purpose flour, and salt. Set aside.

  3. In the stand mixer bowl fitted with a paddle attachment, beat the butter, oil, and sugar on medium-high for 5 minutes.

  4. Add eggs, one at a time to the stand mixer bowl and beat on medium until well incorporated.

  5. Turn the mixer on low and add half of the flour mixture to the butter mixture until fully incorporated.

  6. Add the vanilla and milk, beat on low until incorporated. Scrape down the sides of the bowl. Finish by adding the remaining flour mixture, add a few drops of neon green gel food coloring, and mix on medium for another 30 seconds.

  7. Evenly distribute the cake batter among the three cake pans and bake for about 30-35 minutes or until a toothpick inserted into the center of each cake comes out clean or with just a few moist crumbs.

  8. Remove cakes from oven and let cool in pans for 10 minutes before inverting onto cooling racks to cool completely. Wrap cakes in plastic wrap and place into the freezer to chill for 30 minutes.

Purple Vanilla Buttercream

  1. In the stand mixer bowl fitted with the paddle attachment, beat the butter on high until light and fluffy, about 5 minutes.

  2. Turn the mixer to low, gradually add powdered sugar, followed by the cream. Then add vanilla extract and salt. Mix until incorporated completely. Scrape down sides of the bowl.

  3. Turn the mixer to medium-high and beat the buttercream for about 5 minutes until light and fluffy. Scrape down sides of the bowl. Turn the mixer on low and mix for 2 minutes to push out any air bubbles.

  4. Add 1-2 drops of electric purple gel food coloring to color the buttercream a bright purple.

Black Mirror Glaze

  1. In a small bowl, add water and sprinkle the powdered gelatin over the water. Use a spoon or rubber spatula to mix the gelatin thoroughly. Set aside to bloom the gelatin for 5 minutes.

  2. In a medium bowl, add white chocolate chips and set aside.

  3. In a medium saucepan and medium-high heat, combine the corn syrup, sugar, water, and sweetened condensed milk. Bring to a boil.

  4. After the mixture has reached a boil, turn the heat to low, add in gelatin and stir with a rubber spatula and whisk. Continue to stir until the gelatin has melted.

  5. Pour the hot mixture over the white chocolate chips. Let the hot mixture melt the chocolate chips for 2 minutes before mixing with a whisk. Continue to stir until the chocolate has melted.

  6. Then add a drop of black gel food coloring. Mix until incorporated.

  7. Place a strainer over a large measuring cup, and pour the black glaze over the strainer to remove any remaining clumps.

  8. Occasionally stir the black glaze to reduce the temperature between 85 °F-90 °F before pouring over the apple and cake.


  1. Place a small (6-inch) cardboard on top of a larger (8-inch or 10-inch) cake board attached with painters or masking tape.

  2. Layer one neon green vanilla cake, cut side up onto cake board. Add a 2/3 cup of purple vanilla buttercream over the cake.

  3. Place another cake layer cut side down over the top. Repeat the process for another layer — Crumb coat with purple vanilla buttercream and freeze for 30 minutes.

  4. Add a thick layer of purple buttercream all over the cake. Use an offset spatula to fill in any gaps with more buttercream.

  5. Then use a cake scraper to smooth out the sides of the cake. Use the offset spatula to make the top edges sharp and smooth — place the cake in the freezer for 20 minutes to set buttercream.

  6. Place the cooling rack into the baking sheet pan and set aside.

  7. Cut out a skull face (2 eyes and 1 nose) out of parchment or wax paper. Then add buttercream or corn syrup to the back of the cutout pieces before placing them onto the granny smith apple.

  8. Carefully separate the cake from the larger cake board and place the cake and apple onto a cooling rack.

  9. Slowly pour the black mirror glaze over the top of the apple. You might need several layers of glaze the apple. Use a toothpick for popping any bubbles that might have formed. Let sit for 10 minutes.

  10. Use a toothpick to remove the paper, cut out pieces carefully. Use a damp cotton swab to clean up any corn syrup or buttercream on the apple.

  11. Then drizzle the black glaze over the edges and top of the cake. Allow the black glaze to drip down the sides. If needed, use an offset spatula to smooth on top of the cake. Let sit for 10 minutes to set before moving the cake to a cake stand or cake board.

  12. Place the apple on top of the cake. It's challenging to move the apple without messing up the glaze once it's set, be sure to plan this out ahead of time.

Recipe Notes

  • Food coloring gets darker over time, so it's best to add the food coloring gradually. 
  • A single batch of this cake recipe makes three, 6-inch round cake layers or two 8-inch round cake layers. Double the cake recipe to make enough cake batter for three, 8-inch cake layers.
  • The black mirror glaze is sticky and difficult to cut through when warmer. So cut and serve this cake at a cold temperature (out of the fridge) instead of room temperature.