Roast peppers under broiler with oven door slightly ajar to allow steam to escape. Place charred peppers in a bowl and cover with plastic wrap. Let cool to handle; peel and seed. Place peppers in a food processor with onion, parsley, garlic, thyme and chicken stock. Purée until smooth.
Preheat oven to 375°F.
Bring a pot of water to a boil for the noodles.
Melt 3 tablespoons butter in a medium saucepot over medium heat. Whisk in flour, cook 1 minute then whisk in milk and season with salt and pepper. Stir in sour or heavy cream and thicken sauce. Combine with paprika and pepper purée.