Lemon Blueberry Muffins Ingredients 1 cup butter 1 cup sugar 4 eggs, separated 2 cups all-purpose flour 2 teaspoons baking powder 1 teaspoon salt 1/2 cup fresh lemon juice 2 teaspoons grated lemon rind 1 cup blueberries Step by Step Instructions STEP 1Beat butter until fluffy, add sugar, beating well. STEP 2Add egg yolks, 1 at a time, beating after each addition. STEP 3Combine flour, baking powder and salt. Add to butter mixture alternatedly with lemon juice. Beat at low speed. Stir in lemon rind. STEP 4 Beat egg whites at high speed until stiff peaks form. Gently fold beaten egg whites into batter. Stir in berries and spoon into muffin cups. STEP 5 Bake at 375 degrees for 18 minutes until toothpick comes out clean.