Char pepper in broiler (or over gas flame) until blackened on all sides. Place inside a plastic or paper bag and seal. Allow to stand 10 minutes at room temperature to steam. Remove charred peel, membranes and seeds inside, and cut into very thin strips.
Steam pumpkin/squash cubes until tender, about 10 minutes (may take longer). Set aside.
Heat butter and olive oil together in large skillet over medium heat. Add shallot and cook, stirring for about 3 minutes. Add garlic and cook an additional minute.
Add mushrooms. Stir, seasoning with salt and pepper. Cook for about 3 minutes, or until tender.
Add pumpkin/squash cubes to skillet and stir. Cook for one minute.
Pour wine into skillet and allow to boil until liquid is reduced by half.
Add the cream to the skillet and boil until the sauce thickens and coats the back of a spoon, about 4-5 minutes. Mix in bell pepper and heat, tossing vegetables lightly. Add parsley, stir, and taste to see if more salt and pepper are needed.
Meanwhile, boil pasta according to package directions, stirring from time to time to avoid sticking.
Drain pasta. Add to sauce and bring to simmer. Toss gently. Divide pasta among plates and serve immediately.
(Optional: offer grated Parmesan for topping.)