Preheat oven to 350°F (176°C). Grease a large (12 x 17 inch) rimmed baking sheet well.

Add the eggs, milk, salt, and black pepper to a blender. Blitz for about 30 seconds, or until combined. Then, pour the mixture into a large bowl and whisk to combine.

Pour the egg mixture into the prepared baking sheet, and evenly top with diced mushrooms, green bell pepper, and shredded cheddar cheese.

Carefully transfer to the oven and bake for 20 minutes, rotating the pan once during baking to ensure even cooking. The eggs should be set in the center and no longer jiggle when the pan is gently shaken.

Cook the vegan sausage patties on the stove according to package instructions.

Cut the baked eggs into 12 even squares, approximately the size of the English muffins. Open each muffin and layer on a slice of the sheet pan eggs, a cooked vegan sausage, and then a slice of cheddar cheese.

Wrap each sandwich tightly in parchment paper or foil, then store in a freezer-safe bag or container. Refrigerate for up to 5 days, or freeze for up to 3 months.

To reheat from frozen: Option 1 (preferred) – Thaw in refrigerator overnight. Remove parchment/foil and wrap in a damp paper towel. Microwave in 30-second intervals until warmed through, about 2 minutes. Option 2 – From frozen, remove parchment/foil and wrap in a damp paper towel. Microwave on defrost setting for 1 minute, flip, then microwave in 30-second intervals until warmed through, about 1 minute. Option 3 – From frozen, place parchment/foil-wrapped sandwiches in a 350°F air fryer for about 10 minutes or until warmed through.