Melt butter in a skillet over medium-high heat, and add onion, green bell pepper, and celery. Cook until softened, approximately 5 minutes.
Add chopped garlic and cook 30 seconds to 1 minute longer. Add cornstarch and stir until thoroughly mixed.
Add stewed tomatoes, tomato sauce, Worcestershire, Old Bay, chili powder, hot pepper sauce and red pepper flakes. Turn down to medium heat and stir until thoroughly mixed and bubbling.
Add shrimp and cook until opaque (approximately 5 minutes).