Fill a large pot with lightly salted water and bring to a boil. Cook egg noodles in boiling water until tender yet firm to the bite, 7 to 9 minutes. Drain and set aside.

Preheat the oven to 350 degrees F (175 degrees C).

Heat a medium skillet over medium-high heat. Cook and stir beef, onion, bell pepper, and garlic in the hot skillet until beef is browned and crumbly, 5 to 7 minutes. Drain excess fat from the skillet. Stir in cooked egg noodles, pizza sauce, pepperoni, and milk until well combined. Pour mixture into a 2-quart casserole dish.

Bake in the preheated oven for 20 minutes. Sprinkle with cheese and continue baking until cheese is melted, 5 to 10 more minutes.