Preheat the oven to 350F (180C) degrees. Grease and flour a 9x13 inch cake pan. For a layer cake, line the bottom of the cake tins with rounds of parchment paper. Then grease and flour the sides of the pans.

In a medium bowl sift together the flour, baking powder, baking soda and salt. Whisk together and set aside.

Combine the buttermilk and freshly squeezed lemon juice. Whisk with a fork and set aside.

In a large bowl beat together the butter, sugar and lemon zest until fluffy. (About 2-3 minutes).

Add in the vanilla extract and beat in the eggs 1 at a time.

With the mixer on low speed, beat about 1/3 of the flour mixture into the butter mixture. Then mix in about 1/2 of the milk and lemon juice mixture. Turn off the mixer and scrape down the sides and bottom of the bowl. Repeat the process. Do not overmix.

Toss the blueberries with the 2 teaspoons of flour, then gently fold into the batter.

Pour the batter into the prepared pan/pans. Bake for 30-35 minutes for a 9x13 inch pan or about 25-30 minutes for layer cakes.

Cool the cakes in the pan. Be very careful when inserting the pans.

Beat the butter until soft, then mix in the cream cheese and lemon juice. Gradually mix in powdered sugar until desired sweetness is reached.

Frost the cooled cake with frosting.

Slice with a thin, sharp knife.