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Nerdy Nummies Recipe: Geode Cupcakes (Cookbook Recipe)

Geek is cool—and now it’s also delicious, thanks to Rosanna Pansino’s recipes, creator and host of The Nerdy Nummies, YouTube’s most popular baking show. These scrumptious, quirky Nerdy Nummies Geode Cupcakes are from her brand-new The Nerdy Nummies Cookbook, which is chock full of “sweet treats for the geek in all of us.”

Nerdy Nummies Geode Cupcakes

  • White fondant
  • Chocolate fondant
  • 3 cups sugar
  • 1 cup water
  • Purple liquid food coloring
  • White cake batter
  • 1 tub (16 oz) buttercream frosting
  • Assorted colors of hard candies (Jolly Ranchers)
  • Purple sanding sugar

1. To make a geode, roll out the white and chocolate fondant into 1/8-inch-thick rounds about 5 inches across, making the chocolate one a little bit bigger. Repeat this for a second geode (you can make more geodes if you like, as you will have leftover fondant and sugar syrup).

2. For each geode, line a small bowl with several layers of aluminum foil, crumpling the foil unevenly on the inside to make a unique rock-shaped shell.

3. Cover the aluminum foil with the chocolate fondant. Lay the white fondant on top of the chocolate.

4. In a medium saucepan, combine the sugar and water. Whisk constantly over low heat until all the sugar is dissolved. Add 4 drops of purple food coloring. Whisk until the color is completely blended, and remove from the heat.

5. Spoon the purple syrup into the fondant cups until almost full.

6. Completely cover your geodes with aluminum foil and let sit for at least 12 hours, giving the sugar time to crystalize.

7. Take your geodes out of the foil enclosure. Over a bowl, puncture the center of the purple sugar with a sharp knife. Allow the liquid to drop out into the bowl and then carefully scrape out the excess sugar.

8. Prop the geodes, crystal side down, over a bowl for at least 2 hours to let the excess liquid drip out and the sugar crystals to dry. You can place them on top of lollipop sticks for this step.

9. Once the sugar in the center of the geodes is dry, trim off the excess fondant around the edges with a knife.

10. Preheat the oven to 350°F. Line 24 cups of 2 muffin tins with brown paper liners. (Or bake in batches with 1 muffin tin).

11. Prepare the white cake batter. Fill each muffin cup two-thirds full with batter.

12. Bake until a wooden pic inserted in the center of the cupcake comes out clean, 18 to 20 minutes.

Let the cupcakes cool completely before decorating.


1. Frost the cupcakes with buttercream frosting.

2. Place the hard candies in plastic bags, dividing them by color. Use a hammer or rolling pin to crush the candies so you have large and small pieces.

3. Set aside 4 of the cupcakes. Over the remaining cupcakes, sprinkle the smaller pieces of hard candy all over the tops. Place the larger pieces of the hard candies in the center of the cupcakes to make crystal formations.

4. Dip the 4 reserved cupcakes in the purple sanding sugar. Carefully cut the geodes in half and place one in the center of each cupcake.

5. Enjoy!

Rosanna Pansino is the star of her online cooking show, Nerdy Nummies, where she shows you how to create all sorts of delicious treats. The Nerdy Nummies Cookbook showcases many of her wonderful, creative, and above all, nerdy recipes.

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