Preheat Oven and Prepare Pan: Preheat your oven to 350°F. Grease a 9-inch square baking pan and set aside.
Toss Blueberries: In a small bowl, toss 2 cups of blueberries with 2 tablespoons of flour to coat them. This prevents them from sinking to the bottom of the cake. Set aside.
Mix Lemon Juice and Milk: Add 2 tablespoons of lemon to a measuring cup then pour in enough milk to reach the half cup line. Set this aside and allow the milk to thicken as it sits. (This step is essentially making buttermilk. I never have buttermilk in my fridge and I refuse to buy a half gallon gallon for one recipe here and there. If you happen to keep buttermilk on hand, you can absolutely substitute the milk & lemon for straight buttermilk)
Cream Butter and Sugar: In a large mixing bowl, cream together the softened butter, lemon zest, and 1 cup of sugar until light and fluffy. (personal note-this mixture will smell divine once beaten together, stop and take a moment to smell the yummy flavors! This is why we cook, enjoy the process friend!)
Add Egg and Vanilla: Beat in the egg and vanilla extract until well combined.
Mix Dry Ingredients: In a separate bowl, whisk together 2 cups of flour, baking powder, and salt.
Combine Wet and Dry Ingredients: Alternately add the dry ingredients and the milk to the wet batter mixture, starting and ending with the dry ingredients. Stir just until combined. (use a spatula for this and scrape down the edges of the bowl so their are not any pockets of dry ingredients)
Add Lemon Juice and Blueberries: Gently fold in the flour-coated blueberries.
Pour into Pan: Spread the batter evenly into the prepared pan.
Add Extra Blueberries and Sugar: Sprinkle the remaining ¼ cup of blueberries over the top of the batter and lightly press in. Then, sprinkle the top with the remaining 2 tablespoons of sugar.
Bake the Cake: Bake for 45 minutes, or until a toothpick inserted into the center of the cake comes out clean.This is a thick cake, if the inside is still not set after 45 minutes, cover with foil so the top doesn’t burn and continue cooking in 5 minute increments until baked through.
Cool and Serve: Allow the cake to cool before cutting into squares. Serve as a delightful breakfast treat!
Optional Glaze: If you love a sweet glaze on your bread like I do, whisk together 1 cup of powdered sugar and 1-2 tablespoons of lemon juice or milk until combined and pour over the cooled cake. Mix in a couple of fresh blueberries to the glaze if you’d like to achieve a bright pink color!