COOK pasta as directed on package, omitting salt.
MEANWHILE, heat oil in large skillet on medium heat. Add onions, peppers and garlic; cook 5 min. or until crisp-tender, stirring frequently. Add meat; cook until browned, stirring occasionally. Add diced tomatoes, marinara sauce, 2 Tbsp. Parmesan and seasonings; mix well. Simmer on medium-low heat 10 min., stirring occasionally.
HEAT oven to 350ºF. Drain pasta. Add to meat mixture in skillet; stir to evenly coat. Spoon half the pasta mixture into 3-qt. casserole sprayed with cooking spray; cover with half the VELVEETA. Repeat layers; cover.
BAKE 20 to 25 min. or until heated through, uncovering for the last 10 min. Sprinkle with remaining Parmesan.