Make the Blackberry Lime Cake:

1. Preheat oven to 350F. Butter and lightly flour three 8″ round pans. Line with parchment paper circles.
2. Whisk together flour, baking powder, baking soda and salt. Zest limes and whisk into flour. Set aside.
3. In a small bowl, combine milk and lime juice.  Stir to combine and set aside for milk to curdle.  This is similar to making homemade buttermilk.
4. In the bowl of a stand mixer, beat butter and sugar on medium-high using the paddle attachment.  Beat until pale and fluffy, about 3 minutes.
5. With the mixer on low, add eggs one at a time.  Mix well after each egg.
6. Add vanilla extract and mix to combine.
7. Add the flour mixture in three batches, alternating with the milk, beginning and ending with the flour mixture.  Do not over mix.  Stop the mixer and scrape down the bowl and the mixer blade.
8. Divide batter evenly between the three 8″ round pans.
9. Bake for 25-27 minutes, or until toothpick inserted into center comes out clean.
10. Let cool in pans for 5 to 10 minutes, then remove to wire rack to finish cooling.

Make the Blackberry Reduction:

1. Combine blackberries, sugar and lime juice in a pan over medium heat.
2. Cook 10 to 15 minutes until the juices are bubbly and the berries are soft enough to smash with the back of a spoon.
3. Press the mixture through a fine mesh strainer into a clean bowl to remove the seeds. Use the back of your wooden spoon to really press as much pulp through as you can. Scrape the underside of the strainer to get all of the accumulated blackberry pulp. Discard seeds and return strained puree back to the pan.
4. Cook on medium, stirring with a wooden spoon, until reduced to only a few tablespoons, about 10 minutes.
5. Pour into a small bowl and cover with plastic wrap, pushing the plastic down to touch the blackberry reduction so that a skin does not form. Allow to cool.

Make the Blackberry Buttercream:

1. Place egg whites and sugar into the bowl of a stand mixer, whisk until combined.
2. Place bowl over a pan of simmering water to create a double-boiler. Whisking constantly, heat the egg mixture until it registers 160 degrees on a candy thermometer. Carefully transfer the bowl onto the stand mixer.
3. Using the whisk attachment, beat the egg white mixture on high speed for 8 to 10 minutes until the bowl is no longer warm to the touch and the meringue is fluffy, glossy and holds a stiff peak.
4. Switch to the paddle attachment. With the mixer on low, slowly add cubed butter and mix until incorporated.
5. Add vanilla extract and whip on medium-high until silky and smooth, about 3 to 5 minutes.
6. Add blackberry reduction and whip again until incorporated. The buttercream may look like it’s broken at some point. Keep mixing until it is completely smooth.

Assemble the Cake:

1. Place one layer of cake onto serving plate or cake stand and top with about one cup of blackberry frosting.
2. Repeat with second cake layer, more frosting and then last layer of cake.  Crumb coat and frost cake with remaining frosting.
3. Decorate with additional blackberries and edible flowers. Start by laying out blackberries in a crescent shape, spacing them close together but not touching. Tuck in small sprigs of the micro mint here and there, but not everywhere. Next, add the alyssum, using only the top blooming section of each sprig. Add a few extra berries for height if needed. Fill remaining small holes with the micro pepper blooms.
4. Reserve extra berries and blooms to adorn individual slices when serving, if desired.