For the cake:
- 1 cup neutral oil (canola, vegetable)
- 1/2 cup greek yogurt
- 3 eggs, room temperature
- 2 cups sugar
- 1 tablespoon vanilla extract
- 1 1/2 cups buttermilk, shaken
- 3 3/4 cups all purpose flour
- 1 1/2 teaspoons baking soda
- 1 teaspoon baking powder
- 1 teaspoon salt
For the marionberry filling:
- 3 cups frozen marionberries
- 1/4 cup honey
- juice from one lemon
- 1 teaspoon culinary lavender
- 2 teaspoons King Arthur clearjel
For the buttercream:
- 1 1/2 cups whole milk
- 1 tablespoon vanilla
- 1 cup plus 2 tablespoons sugar
- 3 tablespoons cornstarch
- 1 egg
- 2 egg yolks
- 5 sticks unsalted butter, room temperature
To make the cakes:
- Preheat oven to 350 degrees. Lightly spray non-stick on three 8″ cake pans. Line with parchment and lightly spray.
- In the bowl of a stand mixer fitted with the paddle, beat the oil, greek yogurt, egg, yolks, sugar, vanilla, and buttermilk.
- In a medium bowl whisk together the flour, baking soda, baking powder, and salt. Add dry ingredients to wet ingredients and mix until just combined.
- Divide batter, a generous 1 1/2 cups, among cake pans. Bang on the counter to remove any air bubbles.
- Bake 30-35 minutes, until tops are lightly golden and the centers don’t wobble when shaking the pan. Cool on rack for 5 minutes, then remove cakes from pan and continue cooling. Wrap in plastic wrap and refrigerate until ready to assemble the cake.
To make the marionberry filling:
- In a medium saucepan, combine the berries, honey, lemon juice, lavender and clearjel.
- Cook on medium heat until mixture bubbles and thickens. Using an immersion blender, break up berries to desired consistency. Continue cooking for 5-7 minutes. Cool mixture and then place in fridge to thicken up.
To make buttercream:
- In a small saucepan over medium low heat, combine milk and vanilla. Bring to a scald and turn on low heat.
- In a medium bowl, whisk together sugar and cornstarch. Add egg and yolks and whisk together.
- Slowly add in 1/2 cup of the warmed milk and whisk constantly. Repeat with two more 1/2 cup additions until milk mixture is completely incorporated into egg mixture.
- Return mixture to saucepan and cook over medium heat, whisking constantly. Once mixture thickens (about 3 minutes), continue cooking and whisking for another 2 minutes (set a timer).
- Pour custard into large, shallow dish to cool. Place a piece of plastic wrap over the surface of the mixture to prevent a skin from forming. Refrigerate at least 1 hour, roughly to 68 degrees.
- In the bowl of a stand mixer fitted with a paddle attachment, beat the softened butter on medium speed until light and fluffy, approximately 5 minutes.
- Use a rubber spatula to stir the custard mixture. Add a couple tablespoons at a time to the mixing bowl, stopping and scraping down the bowl every few additions.
- Switch to the whisk attachment and whip mixture on medium speed until buttercream is airy, soft and light in color.
To assemble cake:
- Place one cake layer on cake stand and spread a thin layer of buttercream on the top. Fill a pastry bag with buttercream and a piping tip and pipe a rim around the edge of the cake.
- Fill the center with the marionberry lavender jam and add the second layer of cake.
- Repeat process with second layer.
- Flip the third layer of cake upside down – this ensures a flat surface – and place on top. Frost with a decorating tip, or use an offset spatula to spread the buttercream.
- Refrigerate until ready to serve.
Keywords: marionberry, lavender, layer cake, buttercream