Prepare the Blueberries
Start by prepping the blueberries. If using frozen berries, thaw first. Puree 1 ½ cups (198g) of blueberries, then cook them in a saucepan with ¼ cup water over medium-high heat. Reduce to about ¾ cup (181g). If it reduces too much, add a bit of water. Let it cool completely — you can do this step in advance and refrigerate.

Prepare the Cake Batter
Preheat your oven to 350°F (175°C). Grease and flour three 8-inch round cake pans. In a medium bowl, whisk together flour, baking powder, baking soda, and salt. In a separate bowl, combine sour cream, cooled blueberry puree, and oil. Mix with a fork and set aside.

In the bowl of your mixer, cream together the softened butter and sugar until light and fluffy. Add eggs one at a time, mixing well after each addition. Alternate adding the flour mixture and the blueberry mixture to the butter mixture, starting and ending with the flour mixture. Mix just until combined. If using, add a small amount of pink coloring gel to brighten the berry color. Gently fold in the whole blueberries.

Divide the batter evenly among the prepared pans. Bake for about 25-30 minutes or until a toothpick inserted in the center comes out clean. Allow the cakes to cool in the pans for 10 minutes before transferring to wire racks to cool completely.

Make the Lemon Cream Cheese Buttercream
In a large bowl, beat the butter and cream cheese until smooth and creamy. Add lemon juice and lemon zest. Gradually add the sifted powdered sugar, mixing on low speed until incorporated, then beat until fluffy. Adjust the consistency with a little milk if needed.

Assemble the Cake
Once the cake layers are completely cool, spread the lemon cream cheese frosting between the layers and over the top and sides of the cake. Decorate as desired!