Cut the bread diagonally into two triangles. Slice the cheese into triangular pieces.

In a bowl, beat the egg, then mix in milk and a pinch of salt and pepper.

Transfer the egg mixture to a shallow dish and soak the bread slices, flipping them to absorb the mixture for 1–2 minutes.

Place cheese, bacon, and another layer of cheese on one bread slice, then cover with the other slice to form a sandwich.

Heat half the butter in a frying pan, then add the sandwich and cook until golden brown. Flip and repeat.