Preheat your oven to 325 degrees F. Spray three 8-inch or four 6-inch round cake pans with cooking spray. Spray the bottom of the pans, line the bottoms with parchment paper, and spray again. Set aside.

In a medium sized pot, start boiling the water. Once the water is boiling, add in 2 cups oats, stir and remove the pot from the heat. With a lid, cover the pot and let the oats absorb all of the water. (about 15-20 minutes). Let it cool completely (about 20 minutes) before you add it into the cake bater.

In a medium sized bowl, whisk the baking soda, salt, cinnamon, baking powder, ½ cup of oats, and flour. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar together on medium speed until light and fluffy. About 2 minutes.

With the mixer at medium speed, add the eggs, one at a time, scraping the bottom and sides of the bowl in between each addition and mix until combined. After all the eggs have been added, add the vanilla and beat on medium speed for 30 seconds.

Turn the mixer off, add in the cooled cooked oats and the flour mixture, mixing on low just until combined.

Evenly divide the batter into the prepared cake pans, (about 20 ounces of batter in each 8-inch pan ) and with the back of a spoon or a small offset spatula, evenly distribute the batter to the sides of the pan and bake for 28-32 minutes or until the cake is set in the center and a toothpick comes out with just a few moist crumbs on it.

Allow the cake to cool in the pans for about 10-15 minutes and then transfer them out of the cake pans and onto wire racks to cool completely.

Let the cake come to room temperature and if the cakes need to be leveled, level them before wrapping and storing.

If you're not using the cake layers right away, wrap each layer in plastic wrap.

In a small sauce pan over medium heat, combine the blueberries, sugar and water. Stir until combined. Let it continue cooking until the blueberries start to open and it creates a sauce.

Make a slurry by combining the water and the cornstarch. Making sure your blueberry compote is hot, add the slurry (the heat helps activate the corn starch). Stir until it starts to thicken. When you first add the slurry, it will be a light purple. Cook it until it darkens. This means you are cooking out the flavor of the corn starch.

Set aside and let it come to room temperature. As it cools down, it will thicken even more. Press plastic wrap on the top to help prevent a skin from forming.

(You can put it in the fridge, if you desire, to help the cool down process go faster)

Preheat your oven to 375 degrees F. Line a baking sheet with parchment paper and set aside.

In a medium bowl, combine the oats, brown sugar, flour, butter, cinnamon and salt. Mix by hand with a wooden spoon until the mixture resembles clumps of sand. Spread the crumble over the parchment paper and bake for 8 to 10 minutes, stirring halfway through. The crumble should be golden brown. Let it cool completely and then crumble the mixture into smaller pieces, if needed.

In the bowl of a stand mixer fitted with a paddle attachment, soften the butter by creaming it for about 2 minutes.

With the mixer on low speed, add the sifted powdered sugar.

Add the freeze dried blueberries and blueberry emulsion.

With the mixer on medium speed, add the whipping cream and salt.

Turn the mixer to medium-high speed and beat for an additional 5 minutes. The frosting will become lighter in color and texture. With a rubber spatula, beat by hand to beat out any air pockets.

Pipe a small dollop of frosting onto the middle of a cake board to act as glue and hold the cake into place. Place the first cake layer, top side up, on the cake board

Pipe a rim of frosting around the edge of the cake layer. This will help support the cake layers and prevent the blueberry filling from spilling out. Spread about a half cup of the blueberry filling on the cake layer. Note: don’t overfill with the blueberry compote. You can always serve extra on the side.

Sprinkle about half of the crumble over the blueberry filling.

Gently place the second cake layer on top of the filling/crumble and repeat the same process for the second cake layer.

Place the final cake layer top side down on the second layer of filling.

Apply a small amount of frosting to the cake to act as a crumb coat around the entire cake. Freeze the cake for 10 minutes to set the crumb coat.

After the crumbs are locked in, continue to frost and decorate the cake with the rest of the buttercream.