preheat oven to 425°F

oil a 2-quart baking dish

bring a large pot of salted water to a boil

add the noodles and cook to al dente (according to the package directions)

drain and put in the prepared baking dish

toss with the sour cream and Parmesan

meanwhile, heat the olive oil in a large skillet over medium-high heat

add the ground beef and cook, stirring, until no longer pink (about 4 minutes)

add the bell peppers and scallions and cook until crisp-tender (about 3 minutes)

make a space in the pan, add the tomato paste and toast for a minute

sprinkle with the Italian seasoning

add diced tomatoes, stir and bring to a simmer

cook until slightly thickened (about 2 minutes)

pour the beef mixture over the noodles and sprinkle with grated Cheddar

bake on the middle rack until the cheese is melted and the edges are bubbling (about 15-20 minutes)

let stand for 10 minutes before serving