How to Make a Black Light Erupting Volcano Cake

Three Parts:Preparation of the board and staging areaMaking the cakePresentation

This delicious and exciting confection is guaranteed to steal the spotlight at any social gathering. Perfect for any age, gender, and occasion, the black light erupting volcano cake combines explosive flavor with a burst of fun.

The cake, which serves up to 40 people, will take approximately 4.5 hours to make. Basic baking skills are necessary and baking as a team (1-3 people) is very helpful.


Note: Cake mix, eggs, and oil measurements will change based on the type and brand of cake you use. Check the directions on the back of the cake box to determine the exact measurements for the above ingredients.

  • 5 boxes of cake mix (You will need enough mix to make 7 round cakes: 3-12" and 4-10")
  • 2 dozen large eggs
  • 1 bottle canola oil
  • 2 16 oz tubs chocolate frosting
  • 1 16 oz tub buttercream or vanilla frosting
  • 2 3 oz (85g) boxes green Jell-O
  • 4 tablespoons sugar
  • 3 liters (101.44 fl oz) tonic water (two liter (67.6 fl oz) bottle + one liter (33.81 fl oz) bottle)
  • 1 tube Mentos candy


  1. 1
    See the list of "Things You'll Need" below as well as the "Ingredients" and "Tips", to be sure that you have everything to get started.

Part 1
Preparation of the board and staging area

  1. 1
    Cut a 15" x 15" (38.1cm x 38.1cm) square out of the foam or poster board.
  2. Image titled CoverBoard.JPG
    Cover the foam or poster board square with aluminum foil. Set aside.
  3. 3
    Trace the circumference of the 2-liter (67.6 fl oz) bottle on a piece of the remaining foam or poster board and cut out a stencil. Set aside.
  4. 4
    Using a sharp knife, cut a 1 1/2 inch (3.81cm) length tube from the cardboard tube.
  5. 5
    Make a deep incision 1/2 inch (1.27cm) from the bottom of the tube from Step 4. Set aside. To determine if the incision depth is correct, insert the playing card into the incision. If the card completely covers the inner area of the tube, the incision is deep enough.
  6. 6
    Using the drop cloth, cover the surface ("staging area") that the cake will be presented on.
  7. 7
    Hang one black light above the staging area and lay one black light on either side of where the cake will sit.
    • A fluorescent-tube or compact-fluorescent black light bulb runs cool and puts out much more black light than an incandescent black light bulb.[1]
  8. 8
    Using tonic water (from the 1-liter bottle) instead of tap water, follow directions on the Jell-O box to make 6 oz (170g) of Jell-O (or other brand of gelatin dessert) in a plastic container.
    • The quinine in the tonic water will glow under the black light.[2]
    • The quinine is bitter, so a sour Jell-O flavor would go well with it. Try lemon or lime. You might want to add extra sugar. Start with a tablespoon and mix in well, but feel free to add another, and another, to taste.
  9. 9
    Cover the Jell-O container and place on a level refrigerator shelf for at least 4 hours.

Part 2
Making the cake

  1. 1
    Preheat the oven to 350ºF/180ºC if you are using a shiny metal or glass pan. (Preheat to 325ºF/162.7ºC if you are using a dark or nonstick pan).
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    Use one teaspoon of canola oil to grease the bottom and sides of the 12" (30.48cm) cake pan.
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    Follow the instructions on the back of the cake box to prepare the cake batter.
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    Slowly pour cake batter into the center of the cake pan while scraping the inside of the mixing bowl with the rubber spatula.
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    Bake on middle oven rack for the amount of time listed on the cake box, or until a toothpick inserted in the center of the cake comes out clean.
  6. 6
    Let cake cool for 10 minutes or refrigerate for 5 minutes before cutting.
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    Flip cake pan upside down and lightly shake cake onto the foil-covered square.
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    Use the stencil and a sharp knife to cut the center out of the cake. Set the cake center aside.
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    Flip the cake right side up onto the center of the pan or plate on which the cake will be presented, stacking each layer upon the last.
  10. 10
    Using a paper towel, wipe the extra cake out of the inside of the cake pan.
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    Repeat Steps 2 -10 two more times so there are three 12" (30.48cm) layers of cake, inserting the full 2-Liter of tonic after each layer is stacked to ensure they are properly aligned.
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    Repeat Steps 2 -10 four more times using the 10" cake pan. Pour only half of the cake batter into the 10" (25.4cm) pan and modify the bake time accordingly.
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    Cut a small hole (approximately 1 1/2 inches/3.81cm in diameter) in the center of two of the unused cake centers. These will be used as the top two layers of the cake.
  14. 14
    Microwave the chocolate frosting (top off) for 10-30 seconds depending on microwave strength.
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    Use a knife to gently spread the chocolate frosting over the outside of the cake, filling in the crevices between each layer.
  16. 16
    Carefully move the cake to the staging area.

Part 3

  1. 1
    Tear two of the remaining cake centers in half and place two halves on either side of the cake where the glow stick trees will stand.
  2. 2
    Crack and shake the glow sticks, then gently press the glow sticks' flat ends into the center of the cake "rocks".
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    Open four umbrellas and push the toothpick ends through the plastic loops on top of the glow sticks with the open umbrellas facing forward.
  4. 4
    Take the Jell-O out of the refrigerator and use a spoon to stir and smash the Jell-O into clumps.
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    Spoon the Jell-O onto the staging area surrounding the cake. Pour some on the rocks and around the edges of the cake layers.
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    Add any extra umbrellas or Jell-O to the cake as desired.
  7. 7
    Remove the top two layers of the cake and slowly unscrew the cap of the tonic water, so that it will not fizz out of the bottle.
  8. 8
    Microwave the buttercream or vanilla frosting for no more than 10 seconds.
  9. 9
    Using the rubber spatula, cover the top two cake layers (from "Making the Cake" Step 13) with frosting to look like the top of a mountain.
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    Stack the last two cake layers on top of the cake, hiding the top of the 2-Liter bottle.
  11. 11
    Place the cardboard tube (from "Preparation" Step 4) over the open top of bottle.
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    Insert the playing card through the back of the cake and into the incision of the cardboard tube.
  13. 13
    Gently drop three Mentos candies into the tube and onto the playing card.
  14. 14
    As soon as everyone is ready, pull the playing card out and get out of the way! The volcano will erupt within 5 seconds.


  • To avoid cracking as the cake cools, use a moist cake mix, such as Betty Crocker Super Moist.
  • Do not use flat tonic water.
  • If the cakes begin to crack, lightly spray with water or use chocolate icing to glue them back together.
  • Image titled AluminumFoil.JPG
    If baking the cake in advance, cover the finished cake with aluminum foil for up to 24 hours before presentation.


  • Always use an oven mitt when removing cake pans from the oven to prevent burns.
  • Turn the black lights off when not in use. Lengthy exposure to black lights can damage your eyes.
  • Watch frosting in the microwave to prevent the frosting from exploding.
  • Exercise caution when using sharp objects.

Things You'll Need

  • Measuring cups/spoons
  • Large mixing bowl
  • 12" x 2" (30.48cm x 5cm) round cake pan
  • 10" x 2" (25.4cm x 5cm) round cake pan
  • Whisk
  • Rubber spatula
  • Aluminum foil
  • 6 oz plastic container
  • 22" x 28" (55.9cm x 71.1cm) stiff foam or poster board
  • Drop Cloth
  • 5 toothpick cocktail umbrellas
  • 4 6" (12.5cm) safety light sticks or commercial glow sticks
  • Toothpicks
  • Paper towel
  • 3 24" black lights
  • Playing card
  • 1" diameter cardboard tube

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