This rich and fluffy chocolate lavender cake is made with four decadent chocolate cake layers + floral lavender-infused buttercream frosting. Set aside some of the buttercream to dye green and purple for piped lavender sprigs as decoration.
Preheat the oven to 350°F. Grease two 8-inch round cake tins.
Pour the milk and lemon juice or white vinegar in a small bowl. Let it sit for 10-15 minutes at room temperature to curdle & become homemade buttermilk.
In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, unsweetened cocoa powder, salt, baking powder and baking soda. Set aside.
In another large mixing bowl, whisk together the two eggs, vanilla extract, vegetable oil and your homemade or store-bought buttermilk.
Add the wet ingredients into the dry ingredients and mix it with a whisk or spatula until there is no dry mixture visible.
Add the hot strong coffee and whisk again until the batter is smooth.
Divide the batter equally between the two cake tins. Bake for 30 to 40 minutes, until a toothpick comes out clean from the center of each cake. Let the cakes cool in the pans for 10 minutes, then remove them from the pans and allow to cool to room temperature on a cooling rack.
Make the Lavender-Infused Buttercream Frosting
In a saucepan, melt the three sticks of butter on medium-low heat. Add the lavender buds and simmer for about 15 minutes, stirring often. Pour the butter through a fine mesh sieve to strain out the lavender. Set the butter in a bowl in the fridge to cool and solidify for a couple hours.
Once you're ready to make your frosting, let your butter sit on the counter to come to room temperature and soften a bit (if needed). Then beat the infused butter in a stand mixer or with an electric hand mixer, until it becomes smooth and fluffy, after about 5 minutes.
Add the powdered sugar, salt, vanilla extract and milk to the butter and continue to beat until it is all combined and fluffy, after 3 to 5 minutes.
Assemble the Layer Cake
Once the cakes are completely cool, level the tops. Then slice them both in half lengthwise to form four equal-sized cake layers. (The edges don't need to be trimmed off the sides of this cake, since it is so moist & the edges don't get very caramelized.)
Place the first cake layer in the center of a plate or cake stand. Spread out a few large dollops of the buttercream on top of the first layer.Place the second cake layer on top of the buttercream, making sure this cake layer is centered on top of the first layer. Spread out a few more large dollops of the buttercream on top of the second layer. Repeat for the third and fourth layers of the cake.
Spread the remaining buttercream on the sides of the cake and smooth it out.Optional: Set aside little buttercream and dye it purple and green. Using piping bags to pipe lavender flower springs onto the decorated cake.
Notes
Baking: Check each cake for doneness, since the cakes could finish baking at different times.
Lavender: Dried lavender is more potent that fresh lavender. If you're using dried lavender, only use one-third the amount.
Decoration: For ease, you can totally leave the sides of the cake unfrosted and serve it as a "naked cake".
Storing: Store your decorated cake wrapped in plastic wrap or in a big airtight container in the fridge. You can also bake and cool the cakes ahead of time & freeze them wrapped tightly in plastic wrap & aluminum foil.