Remember to pull the eggs and butter about 30-45 minutes before starting to bake and leave them on the counter to warm up.
Cake:
Preheat oven to 350°. Grease and lightly flour 3, 8-inch round baking pans. To flour the pans: grease the pans with cooking spray then sprinkle some flour over it. Pat baking pan so that they are lightly covered in flour all over the inside, then turn the pan upside down and lightly pat to discard loose flour.
Beat butter in the electric mixer on medium-high speed, for about a minute. Pour in the sugars and beat for another minute or two, until light and fluffy.
Add eggs, one at a time, beating on medium-high speed after each addition. Once incorporated, stop and scrape the sides and bottom of the bowl with a spatula. Tip: Crack eggs into a small bowl, and then add them to the batter one at a time. This way, you won't accidentally drop the whole egg into the batter.
Whisk together the flour, baking powder, lemon zest, and salt together.
Set the speed to "stir" and add half the flour mixture. ("Stir" is usually the slowest setting on a stand up mixer.)
Add half the buttermilk and vanilla extract.
Add remaining flour and after it's just incorporated, pour in remaining buttermilk and lemon juice. Let it incorporate, stop, and scrape sides and bottom of the bowl.
Fold in blueberries with a spatula until evenly incorporated.
Separate the batter between the 3 baking pans evenly and bake for 20-24 minutes.Tip: use a kitchen scale to make sure there is an even amount of batter in each baking pan.
Carefully run a butter knife between sides of the cake pan and the cake. Let the cakes cool for about 10 minutes and then take them out of the pans. Place the cakes onto a wire rack to cool completely. Tip: gently tap the pans with the cake on the counter on its edges to loosen the cake from the pan. It will release easier.
Frosting:
Note: do NOT add frosting to warm cakes or it will melt! Cakes should be completely cooled to room temperature.
Use a whisk attachment when possible.
Beat butter and cream cheese together, on medium-high speed, until smooth, for a couple of minutes.
Lower the speed to low and beat in powdered sugar and vanilla extract.Tip: Sift powdered sugar before adding to the frosting!
Turn up the speed back to medium-high and beat for another minute, until the frosting is light, smooth, and fluffy.
Frosting the cake:
Once the cakes are cooled completely, use a large serrated knife to trim the very thin layer of the tops off the cake layers, just the domed part, to even the tops of cakes. Place 1 layer on your cake stand or a plate and evenly cover the top with some cream cheese frosting. Repeat with remaining layers and you can frost the cake sides if you wish after.
You can decorate the top of the cake with fresh blueberries, white chocolate, and or candy peels on top, as you wish.
Video
Notes
Make ahead: you can prepare the cakes and the frosting (or one of those) ahead of time. Make sure to store prepared frosting in the refrigerator, in an air-tight container. I recommend storing the cakes in the refrigerator as well but separately. You can either wrap each one air-tight in plastic wrap or place them into a large food storage container with a sheet of wax paper in between each cake. Pull the frosting and the cakes out of the refrigerator about 30-45 minutes before you’re ready to frost the cake to let both warm up to about room temperature
Make it into cupcakes: Use a standard cupcake baking pan, line them with cupcake liners, and fill them about 2/3 full. Bake the cupcakes for 18-23 minutes at 350° and frost with cream cheese frosting when cooled.