Heat electric skillet or griddle to 375°F. Cut each chile into 4 pieces.
To assemble sandwiches, top each of 4 slices of bread with 1 slice Monterey Jack cheese, 1/4 of chiles and 1 slice Cheddar cheese. Top with remaining bread slices. Spread margarine on outside of each sandwich.
Grill sandwiches in skillet at 375°F. (medium heat) for 2 to 4 minutes on each side or until bread is golden brown and cheese is melted.