1. Preheat oven to 350°F (175°C). Grease a 9×13-inch baking dish. 2. Cook jumbo pasta shells according to package instructions until al dente. Drain and set aside. 3. In a large skillet over medium heat, brown the ground beef. Drain excess fat. 4. Add diced onion and bell pepper; cook until vegetables are softened, about 5 minutes. 5. Stir in taco seasoning (chili powder, cumin, paprika, onion powder, garlic powder, oregano, salt, and pepper) and salsa. Cook for another 2-3 minutes. 6. Remove from heat and let cool slightly. Stir in 1/2 cup shredded Mexican cheese blend. 7. Stuff each pasta shell with the taco meat mixture and place in prepared baking dish. 8. In a small saucepan over medium-low heat, combine shredded cheddar cheese, milk, diced tomatoes with green chilies, garlic powder, salt, and pepper. Stir until cheese melts and sauce is smooth. 9. Pour queso sauce evenly over stuffed shells. 10. Cover with foil and bake for 20-25 minutes until heated through and cheese is bubbly. 11. Remove from oven and let cool slightly before serving.