Gather all ingredients and preheat the oven to 350 degrees F (175 degrees C). Grease and flour an 8-inch pan.

Beat butter and ½ cup sugar together in a large bowl with an electric mixer until soft and fluffy; mix in vanilla and salt. Add egg yolks and beat until creamy.

Combine 1 ½ cups flour and baking powder in a bowl; add alternately with milk to creamed mixture.

Toss blueberries with 1 tablespoon flour in a small bowl. Add to the batter and fold in gently.

Beat egg whites in a separate bowl until soft peaks form. Add remaining ¼ cup of sugar, 1 tablespoon at a time, and beat until stiff peaks form. Fold egg whites into cake batter.

Pour batter into the prepared pan. Sprinkle remaining 1 tablespoon sugar over top.

Bake in the preheated oven until a toothpick inserted in center comes out clean, about 50 minutes.

Serve and enjoy!