1. Melt 2 Tbsp. of the butter in small saucepan on medium heat. Stir in flour. Gradually whisk in milk. Add nutmeg and bay leaf. Bring to a boil on medium-high heat, stirring frequently. Reduce heat to medium-low; simmer, uncovered, 1 to 2 minutes or until sauce thickens, stirring frequently; keep warm. Discard bay leaf when ready to use.
2. Preheat salamander or broiler. Top 2 of the bread slices evenly with ham and sliced cheese. Cover with remaining bread slices. Brush outside of sandwiches with remaining 1 Tbsp. of butter. Cook sandwiches in large skillet on medium heat 2 minutes per side or until bread is golden brown.
3. Place sandwiches on half sheet pan. Spoon sauce evenly over sandwiches; sprinkle with grated cheese. Broil 30 to 45 seconds or until cheese begins to brown. Sprinkle evenly with chives; cut sandwiches in half and serve.
Nutritional information per serving: Calories 815; Total Fat 48g; Saturated Fat 28g;