Place bacon strips in a cold skillet and turn heat to medium. Cook bacon for 8-10 minutes, flipping occasionally, until crispy and golden brown. Transfer cooked bacon to paper towel-lined plate to drain excess grease.

Butter one side of each bread slice generously, making sure to spread butter all the way to the edges for even toasting.

Heat a large skillet or griddle over medium-low heat. Place one slice of bread butter-side down in the pan.

Layer 2 slices of cheddar cheese on the bread, followed by 2 strips of crispy bacon broken to fit, then 1 slice of American cheese, and top with 2 more cheddar slices.

Place second bread slice on top with butter-side facing up. Press down gently with spatula to help everything meld together.

Cook for 3-4 minutes without moving the sandwich, allowing the bottom to develop a deep golden-brown crust. Check by carefully lifting one corner with spatula.

When bottom is perfectly toasted, carefully flip the sandwich using a wide spatula. Cook second side for another 3-4 minutes until golden brown and cheese is completely melted and gooey.

Transfer finished sandwich to cutting board and let rest for 1 minute before slicing diagonally. Repeat process with remaining ingredients to make additional sandwiches. Serve immediately while hot.