Preheat the oven to 350 degrees. Grease two 9" cake tins, and line the bottom with a parchment round, also grease the parchment. Then, lightly flour the cake tins as well.

In a separate bowl, combine the 2 1/3 cups of flour, 1 1/2 tsp of baking powder, 1/2 tsp of baking soda, and 1/2 tsp of salt. Mix and set aside.

In your Kitchenaid mixer fitted with the whisk attachment, add the cup of butter and beat for a minute. Next, add in the 2 cups of sugar, 4 tsp of lemon zest, and two tbsp of lemon juice and whip until they're mixed. After this add in the eggs one at a time, mixing to combine after each egg. You may need to scrape down the sides with a rubber spatula to thoroughly combine.

Once the eggs are combined, alternate adding in the buttermilk and the flour mixture, mixing in between each addition. Scrape down the sides, and mix until all the ingredients come together.

Divide the batter equally between the two pans. Place both of the pans on the middle rack of the oven and bake at 350 degrees for 25-30 minutes, or until they are golden brown and when a toothpick is inserted into the middle it comes back out clean.

Remove from the oven and allow to cool in the pan for 15 minutes. Carefully remove from the pan and allow to cool on a cooling rack for another 45 minutes. Once the cakes are room temperature, wrap them in plastic wrap and place them in the fridge to cool for at least an hour.

While the lemon cake is baking, clean out your mixing bowl and whisk attachment and get ready to make the frosting that will go between the cake layers!

To your mixing bowl, add the 4oz of room temperature cream cheese, 3 tbsp of salted butter, and 2 tbsp of lemon zest. Whip until combined. Next, add the pint of blackberries and mix on medium speed. The blackberries will mostly break down, its ok if there are some larger chunks left though.

After this, add the 3 cups of sugar and begin mixing at low speed. Once the powdered sugar is incorporated, turn up to high speed and whip until fluffy.

In a separate medium-size bowl, add one cup of heavy whipping cream and beat with a hand mixer until stiff peaks form. Then, add the whipped cream into the lemon blackberry frosting and mix on low speed until just combined.

Scoop the frosting into another bowl, cover with plastic wrap and refrigerate until it's needed later.

While the lemon cake is chilling in the fridge, in a medium-size heat-proof bowl add 4 egg whites, and 3/4 cup of sugar. Fill a small pot with a couple of inches of water and place it on the stove over medium heat. Next, place the heat-proof bowl containing the eggs and sugar over the pot of water to create a double boiler. The water in the pan should not be touching the bottom of the bowl. While stirring continuously, heat the egg whites/sugar to 160 degrees.

Once the egg whites/sugar reaches 160 degrees, carefully remove the bowl and pour the ingredients into your Kitchenaid mixer again fitted with the whisk attachment. Turn the mixer on high and let it whip the egg whites a meringue with stiff peaks forms.

Next, turn the mixer down to medium and add in 1 cup of unsalted butter 1 tbsp at a time with the mixer continuously mixing. Once the butter is all in add the tsp of vanilla and 1/4 tsp of salt. Whip until the frosting becomes light and fluffy. Cover and set to the side until you're ready to frost the cake. You can refrigerate the buttercream if you need more time, however, it will become very stiff once cold and will need to warm back up before you can easily frost with it. It's best to make it close to when you're ready to frost and leave it at room temperature on your counter.

Slice each of the chilled cake rounds in half so you have 4 cake layers. Place one cake layer on the tray and place 1/3 of the blackberry frosting on top of it. Smooth the frosting around as evenly as you can, and then add the second cake round. Again, add 1/3 of the blackberry lemon frosting to the top of the cake round and evenly smooth out. Repeat, finishing with an unfrosted final 4th cake round as the top.

Next, evenly cover the sides and top of the cake with the Vanilla Swiss Buttercream, smooth with a cake frosting knife. Decorate the top with blackberries and edible flowers!

Either serve immediately or chill to set up the Vanilla Swiss Buttercream and serve later!

Slice and enjoy!