Key Lime Pie Cake with Dairy-Free & Gluten-Free Options

This Key Lime Pie Cake pairs a doctored white cake mix with a tangy homemade key lime filling and a creamy white chocolate graham cracker buttercream. The result is a moist, citrus-forward cake with a luscious, slightly tart filling and rich, textured frosting — perfect for summer or any time you crave bright lime flavor.

Lime Cake

• 1 box (461 grams) white cake mix *can sub gluten-free cake mix

• 1 (85 g) package lime jello powder

• 1/2 teaspoon fine sea salt

• 3/4 cup milk, room temperature *plant-based or regular

• 2/3 cup sour cream, room temperature *plant-based or regular

• 4 large egg whites, room temperature

• 1/3 cup vegetable oil

• 1 tablespoon vanilla extract

• 1 tablespoon key lime juice

Key Lime Filling

• 1/8 cup granulated sugar *use 1/4 cup for a sweeter filling

• 2 tablespoons cornstarch

• 3/4 cup key lime juice

• 1 tablespoon lemon juice

• 1 tablespoon salted butter *plant-based or regular

• optional: green gel food color

White Chocolate Graham Cracker Buttercream

• 2 cups salted butter, room temperature *plant-based or regular

• 6 cups powdered sugar

• 1 cup white chocolate chips *plant-based or regular

• 1 cup graham cracker crumbs *can sub gluten-free graham cracker crumbs

• 1 tablespoon vanilla extract

• 1 teaspoon fine sea salt

• optional: pink gel food color

Instructions

Lime Cake

1. Preheat oven to 350°F and prepare three 6-inch round cake pans with baking spray and parchment paper.

2. In a mixer bowl, whisk together the cake mix, lime jello powder, and salt to break up any clumps.

3. Add the milk, sour cream, egg whites, vegetable oil, vanilla, and key lime juice. Mix until combined, taking care not to overmix.

4. Divide batter between the prepared pans and bake 20–25 minutes, or until a toothpick comes out with a few crumbs.

5. Let cakes cool in pans 10 minutes, then invert onto a cooling rack to cool completely.

Key Lime Filling

1. In a medium pot, whisk together the sugar, cornstarch, and key lime juice until smooth.

2. Cook over medium-low heat, stirring constantly, until the mixture thickens and reaches a boil. Boil for 1 minute, then remove from heat.

3. Stir in lemon juice, butter, and green food coloring if using, until fully combined and smooth.

4. Transfer to a shallow dish, press plastic wrap directly onto the surface, and cool completely.

White Chocolate Graham Cracker Buttercream

1. Melt white chocolate chips in 30-second intervals until smooth; set aside to cool slightly.

2. Cream butter on high speed in a stand mixer until light and fluffy, about 10 minutes.

3. On low speed, add powdered sugar, graham cracker crumbs, salt, vanilla, and pink coloring if using, until combined.

4. With the mixer running on low, slowly pour in the melted white chocolate, then increase to high and mix 4–5 minutes until silky and smooth.

Cake Assembly

1. Level one cake layer on a board or plate and spread about 1 cup of buttercream on top.

2. Pipe a buttercream border around the edge, fill with about 1/3 cup key lime filling, and repeat with the remaining layers. Apply a thin crumb coat and refrigerate 20 minutes.

3. Apply a final layer of buttercream and smooth the sides.

4. Decorate as desired — fresh key lime slices, graham cracker pieces, and white chocolate shavings make a pretty topping. Serve and enjoy.

• Substitute regular limes and lime juice if key limes are unavailable.