Make the Cake Layers

1. Preheat oven to 350˚F. Grease 3 8″ straight edge cake pans. Line with parchment paper and grease.
2. In a medium bowl, sift together flour, baking soda, baking powder, and salt together. Whisk until completely mixed.
3. In a standing mixer or with a hand held mixer and a large bowl, cream butter, sugar, and lemon zest until light and fluffy, about 5 minutes.
4. Whisk in eggs, egg whites, vanilla extract, and lavender extract on a high speed until combined, about 2 minutes, scraping down sides as needed.
5. On a low speed, whisk the flour mixture to the egg mixture until just combined.
6. Still on a low speed, pour in the buttermilk and lemon juice, mixing until just combined.
7. Gently fold in blueberries until just combined.
8. Pour batter evenly into greased layer pans. Bake for 25-30 minutes, until a toothpick comes out clean when inserted into the center of each cake. Set on a wire rack to cool, at least one hour, or frosting will melt.*

Make the Jam

1. In a small pot, stir all ingredients together for the jam over medium high heat.
2. Bring to a boil and gently mash. Turn the heat down to low and simmer, covered, for 10 minutes, stirring occasionally.
3. Pour into a container and let cool completely. Chill until ready to use.

Make the Frosting

1. In a standing mixer or with a handheld mixer, whisk butter and mascarpone until light and creamy. Sift in the powdered sugar. Add lavender extract, vanilla paste, and heavy cream. Whisk until completely smooth.

Assemble the Cake

1. When the cake layers are cooled, place one of the cake layers with the flat side down on a plate or cake stand. With an offset spatula, spread the top with about 1 cup of frosting and 1/3 of the jam.
2. Place the second layer on top of this frosted layer and spread another 1 cup of frosting and another 1/3 of the jam.
3. Add on the final layer, flat side up to make the cake even. Lightly frost the rest of the cake with half of the remaining frosting. Mix a couple spoonfuls of frosting with the remaining jam. Frost the tops and sides of the cake with the mixture as desired. Place cake in fridge and chill for 10 minutes.
4. Remove cake from the fridge and frost with remaining frosting. Garnish with fresh blueberries, lemon slices, and culinary lavender buds.
5. Place in the refrigerator to chill for 30 minutes to an hour, until frosting is set.
6. Cover cake tightly and store in the fridge for 4-5 days.