Heart-Shaped Geode Cake
A fun and unique idea for a Valentine's Day or anniversary cake - make a deliciously gorgeous Heart-shaped Geode cake!
Servings: 16 servings
Calories: 750kcal
Equipment
- Small paring knife (to cut the geode shape)
- 1 large piping bag + star tip (linked is a set that contains both)
- silk or food-safe flowers (optional; for decorating)
Ingredients
Red Velvet Cake Layers:
- 3 cups cake flour (you can use all-purpose, but the cake crumb will be a little less delicate)
- 1/4 cup unsweetened cocoa powder
- 3 cups granulated sugar
- 2 1/2 teaspoon baking powder
- 1 teaspoon salt
- 3/4 cup unsalted butter (or 1 1/2 sticks; room temperature)
- 1 Tablespoon vanilla extract
- 1 cup egg whites (about 7 large egg whites)
- 1 1/2 cups buttermilk (room temperature)
- 1/3 cup vegetable oil
- Red gel food coloring (I used Americolor super red (I used at least 10 large drops; add until you reach the shade of red that you like!))
Cream Cheese Buttercream Frosting:
- 8 oz cream cheese (one package; softened)
- 1 cup butter (16 T or two sticks; room temperature)
- 6 cups powdered sugar
- 2-4 Tablespoons milk
- 1 Tablespoon clear vanilla extract
- 1/4 teaspoon salt (if using unsalted butter)
Decorations
- 1 drop soft pink gel food coloring (save and add later)
- 10 large drops Red gel food color (save and add later; you’ll color the geode and the leftover frosting after you’ve covered the cake to pipe the decorative rim)
- Pink Sugar Pearl sprinkles
- 1 cup Rock candy crystals (I also found a pair of tweezers handy for placing rock candy into the ‘geode’ base)
- 3-4 small sheets Edible silver leaf (or silver lustre dust / edible paint)
Instructions
Red Velvet Cake layers
- Preheat oven to 350°F. Prepare three 8 inch round pans with baker's floured spray (or grease and line with parchment rounds).
- Mix together all dry ingredients (flour, cocoa powder, baking powder, sugar, and salt) in a stand mixer with a paddle until fully combined.
- Mix butter slowly into the dry mix, one tablespoon at a time on a low speed. Continue to mix until no large chunks of butter remain, and the mixture looks crumbly.
- Pour in egg whites, and mix on low until just incorporated. Combine buttermilk, vanilla, and oil, and mix on low until fully incorporated. Scrape down the sides of the bowl with a spatula, then beat on medium high for about 30 seconds. Add gel food coloring.
- Divide batter evenly between the prepared cake pans (I find a kitchen scale helpful for this part). This guarantees your layers will bake to be the same height.
- Bake for 33-37 minutes (or until a toothpick comes out clean). Allow cake layers to cool for 10-15 minutes on a wire cooling rack before removing from pans – it helps to run an offset spatula or knife around the perimeter of the pan first. Cool completely before frosting. Set in the fridge or freezer to accelerate the cooling process if desired. (This is a great time to make your frosting!)
Cream Cheese Buttercream Frosting
- Beat together softened cream cheese and butter; slowly add in powdered sugar alternating with milk until frosting reaches desired consistency. Add vanilla and salt if needed and beat until well combined.
Assembly
- Once your cakes are cool, level them (if needed). Place a smear of frosting on your cake circle (to keep the cake from sliding while you decorate it) and center your first cake layer in the center of the circle.
- Spread the layer with frosting, and add the next layer on top. Repeat the process with your remaining cake layers.
- Now you're ready to crumb-coat . If you're unfamiliar with crumb-coating, it's just what it sounds like – spreading a thin layer of frosting over the entire outside of the cake to keep crumbs out of your final layer. I usually do this with my large offset spatula.
- Once your crumb coat has set (this takes about 5-10 minutes in the fridge), add your final layer of frosting and smooth. I like to use a large offset spatula and pastry cutter/bench scraper for this part.
- This is optional, but if you want to add a bit of pink to the outside of the cake – I took maybe a ¼ cup of frosting and tinted it pink, then ‘smudged’ the outside of the cake and re-smoothed. Up to you!
Now for the fun part! Carving the Heart Geode!
- (I cut a piece of paper to use as a template, so that I could keep the sides of the heart even.) Cut about 1 – 1 ½ inches into the side of your cake as you carve the heart shape out; you want the heart to look deep enough to be a convincing 'geode' but not compromise the structure of the top of the cake. (and feel free to eat the cake scraps!)
- With a small offset spatula, re-crumb-coat the geode ‘hole.’ This will both keep crumbs in and hold your rock candy in place.
- Press rock candy crystals into the frosting to cover the base of the geode ‘hole.’ I found tweezers handy for reaching the deeper parts.
- To color the geode, use a bit of gel color with a bit of vanilla extract (so it dries more quickly) and brush into the center/deepest part of the geode. Add a lot of color at the center and continue to thin the color with vanilla extract to make it progressively lighter toward the outer edges.
- Rim the outside of the geode with edible silver leaf to highlight the heart shape. (I tried a few methods for transferring it, because it’s VERY fragile and a bit finicky. Tearing off and moving bits at a time with a dry paintbrush has been my favorite method so far!)
- Finish it off with a few extra pieces of silver leaf and some silk flowers if you’d like – and you’re done! Find someone to give you a high-five! ;)
Video
Nutrition
Serving: 1slice (1/16th cake) | Calories: 750kcal | Carbohydrates: 99g | Protein: 6g | Fat: 38g