Whisk the eggs, milk, maple syrup and cinnamon in a shallow dish.
Form the sausage into six thin patties and cook them for 4 minutes per side until browned and 160°F.
Melt the butter on a griddle over medium heat, dip the bread briefly in the custard and cook for 2 to 3 minutes per side until golden and 160°F in the center.
Cool the French toast and sausage completely.
Build six sandwiches with two toast slices, one sausage patty and cheddar, wrap in parchment and foil, and freeze for up to 1 month.
Remove the foil and microwave in parchment for 2 minutes, then continue in 30-second bursts until the center reaches 165°F.