In a large, heavy-bottomed pot, melt the butter over medium heat until just bubbling. Add the sausage and break up into crumbles, then season with salt. Brown for 2 minutes on 1 side, then stir and brown on the other side for 2 minutes more.
Add the onion, season with salt, and cook for 2 minutes, until starting to soften. Add the jalapeño, garlic, and tomato paste. Stir to distribute the tomato paste. Add the Jazzy spice blend and stir to combine.
Add the pasta, red and green peppers, mushrooms, and salt and stir to combine. Pour in the tomatoes and stock. Bring to a gentle boil, then reduce the heat to low, cover, and simmer for 10-12 minutes, until the pasta is cooked through and the peppers are tender but not mushy.
Mix in the cream cheese to create a thick, creamy sauce.
Serve garnished with scallions, if desired.