• Preheat the oven to 350F degrees. Grease and flour a 9x13 inch cake pan.
• In a medium bowl sift together the flour, baking powder and salt.
• 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. 
• In a liquid measuring cup whisk together the lemon juice and buttermilk.
• With the mixer on low speed, beat about ⅓ of the flour mixture into the butter mixture followed by about ⅓ of the milk mixture. 
• Continue the process of alternating between the flour & milk until just combined, turning off the mixer and scraping down the sides of the bowl as necessary. 
• Toss the blueberries with the 2 teaspoons of flour, then gently fold into the batter with a spatula.
• Pour the batter into the prepared pan. Bake for 25-30 minutes, or until an inserted toothpick comes out clean. 

Cream Cheese Frosting

• Beat the butter until soft, then mix in the cream cheese.
• Add in the lemon juice and mix in 3 cups of the powdered sugar, starting with the mixer on low speed and then turning up to medium as it starts to combine.
• Beat in 1 tablespoon of whipping cream, and then mix in the rest of the powdered sugar as necessary, going little by little and adding more cream if needed. 
• Frost the cooled cake, and optionally decorate with blueberries and lemon slices.