Preheat oven to 425 degrees. Peel and dice apple into tiny pieces. In a small bowl, squeeze lemon juice over apple pieces and stir gently. Coat apple pieces with 2 Tbs. of Bisquick and stir in walnuts. Set aside in refrigerator.In medium bowl, whisk together egg, brown sugar, sugar, cinnamon and milk until smooth. Mix in Bisquick 1/2 cup at a time until smooth (no lumps). Fold in apple mixture. Spray muffin tin or scone skillet with non-stick cooking spray. Fill each section half way to the top. Bake 15-18 minutes at 425 degrees or until golden brown. A toothpick or knife inserted should come out clean. Let cool in pan for 15-20 minutes. Lift scone from each section and finish cooling on a wire rack. When completely cooled, store in air-tight container.