Fennel Gratin with Pecorino and Lemon

Ingredients

• 0.5 teaspoon pepper black
• 3 tablespoons butter 
• 1.5 teaspoons kosher salt 
• 5 large fennel bulb fresh cored trimmed cut into 1/4-inch-thick slices
• 1 tablespoon thyme sprigs fresh chopped
• 3 large garlic clove minced
• 1.5 teaspoons lemon zest finely grated
• 0.5 cup chicken broth 
• 5 tablespoons olive oil 
• 12 ounce onion halved cut into 1/4-inch-thick slices
• 0.8 cup panko bread crumbs (Japanese breadcrumbs)
• 2 tablespoons parsley fresh italian chopped
• 1 cup pecorino cheese 

Equipment

• frying pan
• oven
• pot
• baking pan

Directions

1. Lightly oil shallow 2-quart glass or ceramic baking dish.
2. Heat 5 tablespoons oil in large wide pot over medium heat.
3. Add onion and garlic; sauté until softbut not brown, about 5 minutes.
4. Addfennel; increase heat to medium-high andsautéuntil fennel is slightly softened andbeginning to brown, stirring frequently,about 18 minutes. Stir in broth and next 4ingredients. Reduce heat to medium-low;simmer until most of broth is absorbed,about 5 minutes.
5. Transfer to dish.DO AHEAD: Can be made 1 day ahead. Coolslightly; cover and chill.
6. Let stand at roomtemperature 1 hour before baking.
7. Melt butter inlarge nonstick skillet over medium heat.
8. Add panko; sauté until golden, about 3minutes.
9. Remove from heat; cool to roomtemperature. Stir Pecorino, parsley, and peelinto panko. DO AHEAD: Can be made 1 dayahead. Store airtight in refrigerator.
10. Preheat oven to 425°F.
11. Sprinkle pankomixture over fennel.
12. Bake until gratin isheated through and topping is deep golden,about 20 minutes.
13. Serve warm.