Brown the sausage with the onion, garlic and bell pepper in butter in a skillet, stirring until the sausage is crumbly; drain.
Stir in the cayenne pepper and pepper flakes.
Add the mushrooms and cook over low heat for 10 minutes or until tender, stirring occasionally.
Prepare the stuffing mix following the package instructions.
Combine the sausage mixture and stuffing and mix well.
Cook the portobello mushrooms in 1 tablespoon of the olive oil in a skillet over low heat for 5 minutes or until mushrooms are tender.
Remove the mushrooms.
Saute the bell pepper strips in the hot oil for 5 minutes or until tender.
Fill the mushrooms with the sausage mixture.
Garnish with red pepper strips.
Drizzle with the remaining tablespoon of olive oil.
Bake at 350 degrees for 15 minutes.