Preheat oven to 350 degrees. Spray a 9x13 baking dish with cooking spray and set aside..
In a large skillet, brown ground beef until there is no longer any pink remaining. Drain grease.
Add the tomato soup, Rotel tomatoes, salsa, chili powder, paprika, garlic powder, salt and black pepper. Simmer over medium heat for 5 minutes.
Remove from the heat and mix the sour cream into the ground beef mixture.
Add cooked pasta and half of the shredded Monterey and cheddar cheese. Mix everything. Add the cheesy spaghetti into the prepared 9 x 13 baking dish and top with the remaining shredded cheese.
Bake uncovered for 20 minutes until hot and bubbly.
Optional - Garnish with green onions and cilantro.
Notes
Fridge: Store leftover casserole in an airtight container for up to 4 days.
Freezer: Cool the casserole before storing it in an airtight container for up to three months.