Start your day off right with one of these protein-packed egg sandwiches.
Preheat oven (or toaster oven) to 400 degrees. Split English muffin; toast directly on oven rack. Transfer to a rimmed baking sheet (or toaster-oven tray). Spread muffin halves with butter.
Layer bottom half with Canadian bacon, Swiss cheese, and tomato; sprinkle with coarse salt and ground pepper. Return to oven; bake until cheese has melted, about 5 minutes. Top with other muffin half.
Instead of butter, you can spread the muffins with Dijon or grainy mustard; you can also use other types of cheese, such as provolone or cheddar.