Pour broth in a Dutch oven or stockpot; bring to a boil. Add chicken; reduce heat to medium-low, and cook, uncovered, 10 minutes. Remove chicken from broth; coarsely chop, and set aside. Strain broth through a sieve into a saucepan; simmer, uncovered, over medium heat until reduced to 2 1/2 cups (10 to 20 minutes).
Melt 3 Tbsp. butter in a large skillet over medium heat. Sauté red bell pepper and onion 4 minutes or until tender. Add mushrooms, salt, and ground red pepper; sauté 4 minutes. Remove from heat, and set aside.
While broth continues to simmer, preheat waffle iron, and cook waffles.
Melt remaining 3 Tbsp. butter in Dutch oven over low heat; whisk in flour until smooth. Cook 3 minutes, whisking constantly. Gradually whisk in reserved 2 1/2 cups broth and cream; cook over medium heat, whisking constantly, until sauce is thickened and bubbly.
Add chicken and reserved vegetables to sauce. Stir in sherry and lemon juice; cook over medium heat, just until thoroughly heated. Add salt and pepper to taste. Serve over waffles. Garnish, if desired.