Preheat the oven to 350°F. Butter and flour three 6-inch round cake pans.

Beat together the wet ingredients in a medium bowl and set aside.

Sift the dry ingredients together in a medium bowl and coat blueberries with flour.

In a large mixing bowl, beat the softened butter until creamy. Add the flour mixture and mix.

Slowly pour in the wet ingredients and mix until just combined. Fold in blueberries.

Divide the mixture evenly into the cake pans.

Bake for about 30 minutes or until the centers are springy. Cool in pans for 15 minutes.

Place ½ cup of blueberries in the freezer.

Combine remaining blueberries, sugar, lemon juice, and water in a saucepan and cook until berries burst.

Strain blueberry reduction and chill until ready to use.

Beat the butter and salt until fluffy, then gradually add in the confectioners’ sugar.

Beat in the lemon juice until desired consistency is reached.

Mix blueberry reduction into a portion of the frosting.

Pipe lemon buttercream around the edge of one cake layer and fill with blueberry-lemon buttercream.

Repeat with another cake layer and smooth the frosting on the sides.

Pipe lemon buttercream dollops and add frozen blueberries inside. Refrigerate before slicing.