Heat a non-stick skillet over medium heat.
While the skillet is heating, crack the eggs into a bowl, season with salt and pepper, and whisk until well combined.
Pour the eggs into the skillet and scramble them until fully cooked, about 3-4 minutes. Remove from heat and set aside.
In the same skillet, melt 1 tablespoon of butter over medium heat.
Place one slice of bread in the skillet, then layer with one slice of cheddar cheese, the scrambled eggs, bacon or sausage, and the second slice of cheddar cheese.
Top with the second slice of bread and cook until golden brown, about 3-4 minutes.
Carefully flip the sandwich and cook the other side until golden brown and the cheese is melted, about another 3-4 minutes.
Remove from the skillet, slice in half, and serve warm with optional hot sauce or avocado slices.