1. Infuse the lavender milk: Heat the soy milk in a small saucepan over medium heat until it just begins to simmer. Remove from the heat and add the dried culinary lavender. Let it steep for exactly 25 minutes. Strain the milk through a fine mesh strainer to discard the buds and allow the milk to cool completely.

2. Prepare the pans and aquafaba: Preheat your oven to 350°F (175°C). Grease three 6-inch cake pans and line the bottoms with parchment paper. In a medium bowl, measure ½ cup of aquafaba and whip it with a hand mixer on medium-high speed for 1 minute until light and foamy (do not over-whip into stiff peaks).

3. Mix the wet ingredients: In a large bowl, combine the softened vegan butter, neutral oil, granulated sugar, and lemon zest. Beat on medium speed for about 3 minutes until light and fluffy. Mix in the lemon extract, vanilla extract, cooled lavender milk, and the foamy aquafaba.

4. Incorporate the dry ingredients and berries: On low speed, gradually add the cake flour, baking powder, and salt. Mix for 1 to 2 minutes until just combined, scraping the sides of the bowl as needed. Gently fold in the fresh blueberries using a spatula.

5. Bake and cool the cakes: Divide the batter equally among the prepared pans. Bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean. Let the cakes cool in the pans for 10 minutes, then invert them onto a wire rack to cool completely.

6. Make the frosting and assemble: Beat the vegan butter until fluffy. Gradually add the powdered sugar, lemon juice, vanilla, and soy milk until you reach a spreadable consistency (add food coloring if desired). Assemble the cake by placing a layer on a stand, spreading frosting, and adding a thin layer of blueberry jam. Repeat this process. Frost the outside and decorate with fresh blueberries, lemon slices, and a sprinkle of lavender.