Melt butter in a large skillet over medium heat. Cook onion and bell pepper with salt and pepper until soft, about 5-6 minutes.
Add 3 tablespoons parsley, garlic powder, tomatoes, chicken stock, hot sauce, and Worcestershire sauce. Bring to a boil.
Mix cornstarch with 1 tablespoon water in a small bowl; add to the skillet to thicken the sauce. Reduce heat to low-medium.
Season shrimp with salt and pepper; add to sauce. Increase heat to medium, stir, and cover. Cook until shrimp turns pink.
Remove from heat, garnish with remaining parsley, and serve with rice.