Heirloom Tomato Gratin

INGREDIENTS

• extra virgin olive oil
• 2 teaspoons honey
• 1 cup freshly grated Parmigiano-Reggiano cheese
• freshly ground black pepper
• 2 cups whole wheat breadcrumbs
• 3 teaspoons fresh thyme leaves, chopped
• 1 tablespoon minced garlic
• 3 pounds ripe heirloom tomatoes, cut 1/3-inch slices
• 1 large sweet onion, finely chopped
• sea salt