Melt 2 tbs butter in large skillet over medium-high heat. Saute the bell peppers, onions and garlic in the butter for 8-10 minutes until softened slightly. If you like your veggies blackened in this type of dish, like I do, give them a couple more minutes until the edges start to turn black.
While the veggies are cooking, cut the chicken breast into bite size pieces.
Prepare a medium size pan over high heat with the olive oil. When the pan is hot, add the chicken and cook, stirring for 5-7 minutes, or until the chicken is no longer pink.
When the vegetables are softened or blackened to your liking, add the chicken to the pan.
Add the tomatoes, mushrooms, chicken stock, 1/4 tsp salt, cayenne pepper, paprika, pepper and thyme and simmer for 10-12 minutes until thickened. If you like your sauce a little thicker, just add 1/2 teaspoon cornstarch to a couple tablespoons of the liquid from the saucepan. Stir until smooth, remove pan from heat and whisk in cornstarch/sauce mixture, then put back on the heat.
While the sauce is simmering, prepare fettucini according to package directions and serve sauce over plated noodles. Sprinkle a little parsley over each serving to complete.