Step 1

Heat olive oil in a skillet over medium heat. Crack eggs into skillet; cook for 1 to 2 minutes. Flip and cook egg until done, 2 to 5 minutes more. Transfer eggs to a plate and season with salt and pepper.

Step 2

Spread butter onto 1 side of each bread slice.

Step 3

Heat a skillet over medium heat. Lay bread slices in the hot skillet, butter-side down. Quickly layer Swiss cheese, 1 fried egg, Cheddar cheese, 1 fried egg, avocado, and remaining bread slice, butter-side up. Carefully flip sandwich to grill other side until golden brown, 3 to 4 minutes.

Step 4

Remove sandwich from skillet and cut in half.