Chicken-Apple Sausage Breakfast Burritos (Freezable Make-Ahead!)

fully precooked sweet chicken-apple sausage links (about 3 ounces each)

frozen, cubed butternut squash (about 5 ounces of squash) (see note)

finely chopped sweet onion (about 1/4 of a large onion)

finely chopped red pepper

eggs

dried sage

kosher salt

black pepper

Flatout flatbreads (we used Soft 100% Whole Wheat and Light Original)

shredded, reduced-fat cheddar cheese