3 1/3 cups all purpose flour (plus 1 tablespoon for blueberries)
1 1/4 teaspoons salt
1 tablespoon baking powder
1/2 cup (1 stick) unsalted butter, room temperature
3/4 cup peanut oil or vegetable oil
2 1/4 cup granulated sugar
4 large eggs
2 1/2 teaspoons vanilla extract
1 1/2 cups buttermilk
1.2 oz bag freeze dried blueberries (about 1 cup)

Preheat oven to 350 degrees.
Line the bottoms of three 8″ cake pans with parchment paper. No need to butter and flour the pans. *see note
In a medium bowl, whisk flour, baking powder, and salt until well combined.
In the bowl of a stand mixer with the paddle attachment, cream butter and sugar on high for about 3 minutes, or until pale and fluffy. Reduce speed and add oil, then the eggs, one at a time, fully incorporating after each addition. Add vanilla until just combined.
Alternate adding flour mixture and buttermilk, beginning and ending with flour (3 additions of flour and 2 of milk), fully incorporating after each addition.
Add 1 tablespoon of flour & freeze dried blueberries to a food processor and pulse into a fine powder. Its okay if there are a few small chunks left, but get it as fine as possible.
Divide about 1/2 to 2/3 of the batter evenly between the three pans. Mix the freeze dried blueberry powder into the remaining 1/3 to 1/2 of the batter and fold in to combine. Divide blueberry batter between the three pans by dotting the tops of the cakes, then use a small spatula or knife to swirl it in.
Bake for 30-35 minutes or until a toothpick or cake tester inserted into the center comes out clean. If using bake-even strips, they may need a few additional minutes.
Transfer pans to a wire rack to cool for 30 minutes. Invert cakes onto rack, peel off parchment, and let cool completely.
If the cakes domed in the oven, you’ll want to slice the very tops of the cakes off to make each layer completely flat and level for a more professional look. You can do this using a very sharp bread knife, or a cake leveler.
If you’re not assembling cakes right away, individually wrap each layer tightly in plastic wrap to prevent drying. Layers can be stored in the refrigerator for a day or two, or frozen (wrapped in plastic wrap first, then aluminum foil) for up to two weeks. You may want to consider brushing the layers with simple syrup if you’re refrigerating or freezing them.

*baker’s note: Not buttering or flouring your cake pans actually helps the cakes keep their shape better when cooling and helps prevent the outer edges of the cakes from overcooking. The parchment will allow the bottoms to release from the pans easily, but you may need to run a knife or a toothpick around the outside edge before turning out of the pans.

Blueberry “Jam” Filling:
(You may also use store bought blueberry jam)
18 oz Fresh Blueberries (about 4 cups)
2 cups sugar
pinch of salt
3 tablespoons corn starch

Reserve about 1/2 cup of the blueberries for the decoration/topping of the cake. Pulse the remaining 3 1/2 cups berries in a food processor just to break them up a bit. Don’t puree them. You can also mash them up with a potato masher instead.
Add the blueberries to a large heavy pot or sauce pan, and stir in the sugar, salt, & cornstarch. The mixture will boil up a lot so a large pot is important.
Bring the mixture to a rolling boil over medium-high to high heat, stirring occasionally, and boil for 15 minutes or until reduced and thickened.
Transfer to a heat safe bowl or container and refrigerate until ready for use. If it’s a bit thinner than normal jam, that’s fine.

Vanilla Swiss Meringue Buttercream Icing:
Adapted from “Layered” by Tessa Huff
3/4 cup fresh egg whites (not pasteurized egg whites)
1 1/2 cups sugar
pinch of salt
2 cups (4 sticks) unsalted butter, at room temperature (cut into 1 tablespoon slices)
2 1/2 teaspoons pure vanilla extract

Place the egg whites, sugar, & salt in a very clean bowl of a stand mixer and whisk them together by hand to combine. Fill a medium saucepan with an inch or two of water and bring to a simmer over medium to medium-high heat. Place the mixer bowl over the saucepan to create a double boiler. Be sure that the bottom of the bowl doesn’t directly touch the water, and that the water doesn’t reach a full boil.
Heat the egg whites until they register 160F on a candy thermometer, whisking regularly to avoid cooking the whites. As soon as they’re at the correct temperature, carefully attach the mixer bowl to the stand mixer and add the whisk attachment.
Beat the egg whites on high speed for 8 to 10 minutes until they hold stiff peaks and the outside of the bowl is cooled to room temperature. Stop the mixer and swap the whisk attachment for the paddle.
On low speed, add the butter, a few tablespoons at a time, waiting for it to incorporate before adding more. Once all the butter is mixed in, add the vanilla extract and mix in to incorporate. Turn the mixer up to medium-high and beat until the buttercream is smooth and silky, about 3 to 5 minutes.
If the mixture starts to look curdled, just keep beating. It’ll come together.
If the whites were still too warm when the butter was added and the buttercream is too thin and soupy, refrigerate the bowl in 10 minute bursts until it’s cool (but not cold) and beat again until smooth.

Assemble cake:
Place the first cake layer on an 8″ cardboard cake round, serving plate, or cake stand. Using a cake round will make it easier to ice and decorate, especially if you have a revolving turntable for decorating (I use a lazy suzan, but you can also just spin your plate or cake stand while you work).

Fit a piping bag with a large round or star tip and fill with a cup or two of the Swiss meringue buttercream. Pipe a thick dam of icing around the outside of the cake to contain the blueberry filling. This will ensure that the filling stays in place and doesn’t squish out when the layers are stacked.

Place about half of the filling in the center of the cake and spread it smooth and even using an icing spatula. Add the next layer of cake, looking from directly over the top and from eye level at the cake to make sure each layer is directly one above the other, rotating the cake to be certain. Repeat the same procedure with the buttercream dam and the other half of the filling, then add the third and final layer of cake and check for straightness again. Using about half of the remaining icing, crumb coat your cake (If you have any icing left in the piping bag, empty it out and use that too). Starting with the top of the cake, spread the icing thin and work some of it down the sides of the cake to completely cover the whole thing in a thin, smooth, even coat of icing. This first layer of icing seals the cake and keeps crumbs from being visible in the outer layer of icing. It may seem like unnecessary trouble, but it really is worth it to get a smooth professional finish on the icing.

Place the cake in the refrigerator for about 30 minutes to an hour to help set the icing and firm up the cake.
Reserve about 1/4 cup of icing for decorating (optional), and spread the remaining buttercream over the whole cake the same way you did the crumb coat. Start by smoothing the top and slowly working the icing down the sides to cover the cake completely. Try to get the icing as completely smooth as possible with straight sides and a flat, level top. I use a long offset icing spatula. If desired, once the icing is smooth, you can use the tip of a small icing spatula or butter knife to create a swirl in the top & sides. Make a small smooth mound in the center of the top of the cake with the reserved 1/4 cup of icing, and cover the mound as completely as possible with the reserved fresh blueberries so it looks like a heaping pile of blueberries. (If you tried to just make an actual heaping pile of blueberries, they’d roll off the top of the cake) If you have some blueberries left, dot them around the mound so they look like they spilled away.

Refrigerate the cake again for at least another 30 minutes to set the icing before covering or serving.

This cake will keep well in a cake saver at room temperature for a day or two if the weather is not too hot or humid. Otherwise, cover tightly and store in the refrigerator for up to 3 days.

If refrigerating, bring cake to room temperature at least two hours before serving.