Next-Level Croque Monsieur

Preheat oven to 450 degrees with rack in bottom third. Blanch broccoli rabe in batches in a pot of salted boiling water until just tender, about 2 minutes. Drain.

Heat oil in a large skillet over medium heat. Add garlic; cook, stirring, 30 seconds. Add broccoli rabe; cook, stirring, 2 minutes. Season with salt. Let cool slightly, then finely chop.

For each sandwich, spread 2 teaspoons jam on one bread slice and 1 teaspoon mustard on another. Layer one slice with cheese, broccoli rabe, and ham, dividing evenly. Close sandwich; brush each side with butter.

Place the sandwiches on a baking sheet, top with 2 tablespoons bechamel and 1/4 cup grated Gruyere. Broil until golden brown and bubbling, about 10 minutes.