Preheat your oven to 350°F (175°C).

In a large skillet over medium heat, melt butter and sauté diced onion until translucent and slightly golden, about 3 minutes.

Add vegetarian meat crumbles to the skillet and cook for approximately 5 minutes.

Transfer mixture to a mixing bowl and add breadcrumbs, garlic powder, rubbed sage, shredded cheese, and eggs. Combine until fully mixed.

Grease a loaf pan and pack the mixture into the pan, smoothing the top.

In a small bowl, mix ketchup and brown sugar for the glaze, then spread it on top of the meat mixture.

Bake in the preheated oven for about 1 hour, or until edges are browned.

Let the meatloaf rest for about 10 minutes before slicing and serving.