Blot chiles with paper towels; mix with cumin and salt.

Divide half the Jack among 4 slices; spread chiles evenly over cheese.

Add remaining cheese; close with remaining bread.

Butter outsides; place in a skillet over medium-low.

Cover; cook 3 to 4 minutes per side. Uncover; cook each side 1 minute more until crisp and fully melted.

Rest 1 minute; cut diagonally.