Preheat your oven to 350°F (175°C).

In a large bowl, combine the oats, salt, and pepper.

In a skillet over medium heat, add a splash of oil and sauté the chopped onions and bell peppers for about 5 minutes until softened.

In the same bowl with the dry ingredients, add the ground beef, sautéed vegetables, Worcestershire sauce, eggs, and milk. Mix everything until well combined, being careful not to overmix.

Shape the meat mixture into a loaf and place it in a greased baking dish or on a lined baking sheet.

In a small bowl, combine ketchup and brown sugar. Spread the glaze over the top of the meatloaf.

Bake for about 45-60 minutes, or until the internal temperature reaches 160°F (70°C).

Let the meatloaf rest for 10 minutes before slicing.