1/2 cup packed dark brown sugar 1/4 cup chopped pecans $ 1 1/2 teaspoons ground cinnamon 1 cup granulated sugar 1/4 cup butter, softened $ 1/2 cup egg substitute 1 cup reduced-fat sour cream $ 2 tablespoons water 1 teaspoon vanilla extract 1 3/4 cups all-purpose flour (about 7 3/4 ounces) $ 1 teaspoon baking powder 1/2 teaspoon baking soda 1/2 teaspoon salt Cooking spray $ 6 tablespoons powdered sugar 3 teaspoons fresh orange juice $ Dash of salt

Preheat oven to 400°.
Combine first 3 ingredients; set aside.
Place granulated sugar and butter in a large bowl; beat with a mixer at medium speed until well blended (about 3 minutes). Add egg substitute; beat 3 minutes. Beat in sour cream, water, and vanilla.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, baking soda, and salt in a large bowl, stirring well with a whisk. Make a well in center of mixture; add sour cream mixture. Stir just until combined.
Place 3 tablespoons brown sugar mixture in a small bowl; set aside. Sprinkle surface of batter with remaining brown sugar mixture. Gently fold batter 4 times.
Place 18 paper muffin cup liners in muffin cups; coat liners with cooking spray. Spoon batter into prepared cups. Sprinkle batter evenly with reserved brown sugar mixture. Bake at 400° for 25 minutes or until a wooden pick inserted in center comes out clean. Remove muffins from pan immediately; place on a wire rack. Cool 10 minutes.
Combine powdered sugar, juice, and dash of salt in a small bowl, stirring until smooth. Drizzle powdered sugar mixture evenly over muffins.