Gather all ingredients and preheat the oven to 350 degrees F (175 degrees C). Grease and flour an 8-inch pan.
Beat butter and 1/2 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 1/4 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!
