Preheat oven to 350°F (180°C). Spray a 10-inch (25 cm) tube pan (angel food pan) or nonstick bundt pan with cooking spray. Set aside.
Sift the cake flour, baking powder, and soda into a medium-sized mixing bowl. In a large mixing bowl, cream the butter with an electric mixer. Add SPLENDA® Granulated and egg. Beat until smooth. Add the egg substitute and vanilla. Beat briefly to incorporate. Add applesauce and half of the sour cream and beat until smooth. Add the sifted flour mixture and beat at medium speed just until smooth. Add remaining sour cream and blend just until incorporated and batter is uniform. Set aside.
Place 1/4 of cake batter in a small bowl. Add brown sugar and cinnamon. Stir well.
Place 1/2 of the remaining cake batter into prepared pan. Top with filling. Swirl with knife. Top with remaining batter.
Bake in preheated 350°F (180°C) oven 50-60 minutes or until a toothpick inserted near the center comes out clean.
Serving Size: 1 slice. Amount per Serving: Total Calories: 200, Calories from Fat: 72, Total Fat: 8 g, Saturated Fat: 5 g, Cholesterol: 25 mg, Sodium: 180 mg, Total Carbohydrates: 28 g, Fibre: 1 g, Sugars: 5 g, Protein: 4 g