Preheat your oven to 350°F (175°C).
In a large skillet, heat the olive oil over medium heat. Add the chopped onion and minced garlic, sautéing until the onion is translucent, about 3-4 minutes.
Add the ground beef to the skillet. Cook until the meat is browned and no longer pink, breaking it apart with a wooden spoon, about 5-6 minutes.
Stir in the drained diced tomatoes, tomato sauce, mixed vegetables, cooked pasta, Italian herbs, salt, and pepper. Mix well and cook for another 5 minutes to combine the flavors.
Transfer the mixture into a greased 9x13 inch baking dish and spread it out evenly.
Top the casserole with the shredded cheddar cheese, ensuring it's evenly distributed over the top.
Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.
Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden.
Let it cool for 5 minutes before serving.