- 1/ 4 cup butter
- 1/ 4 cup all-purpose flour
- 3 cups whole milk
- 2 garlic cloves, finely grated
- 1 sprig sage
- 1 sprig thyme
- 2 cups grated Gruyere, divided
- 1 cup grated Parmesan, divided
- 1 teaspoon lemon zest
- Pinch of nutmeg or cardamom (optional)
- Kosher salt, to taste
- 12 slices sourdough bread
- 18 thick-cut slices ham
Preheat oven to 425°F. In a medium saucepan, melt butter oven medium heat, then stir in flour to make roux. Slowly whisk in milk; add herbs and garlic. Cook until thickened, 5 minutes. Stir in half of the cheeses with lemon zest, nutmeg/ cardamom (if using) and salt. Let cool.
Spread béchamel on all both sides of each slice of bread. Layer with ham and a sprinkle of cheese. Sandwich and top with any remaining cheese. Place on a parchment lined sheet pan, then bake until golden and bubbling, 20-25 minutes. Serve immediately!