Preheat oven to 400° F. Cook sausage in a large skillet over medium-high heat, stirring frequently, until thoroughly cooked and no longer pink. Remove from heat, stir in apple; allow to cool slightly. Stir in Cheddar cheese; add walnuts if desired. Separate dough into 10 biscuits; flatten each biscuit into a 5 1/2-inch circle. Place 2 tablespoons of meat mixture in the center of the circle; drizzle 1/2 to 1 teaspoon maple syrup over the filling in each pocket. Moisten the edges of the dough with a small amount of water; carefully fold dough over mixture to form half-moon-shaped pockets. Press the seam with a fork to seal. Place on ungreased baking sheets. Lightly brush egg mixture on top of each pocket. Sprinkle with a light dusting of cinnamon and sugar. Bake 10 minutes or until golden brown.