Onion Flatbread

Name: Onion Flatbread
Cook time: 30 min
Total time: 30 min
Cuisine: Mediterranean
Ingredients: Flour, for surface; 1 lb. pizza dough, at room temperature; Cornmeal, for baking sheet; 1 1/2 tbsp. Dijon mustard; 4 oz. thinly sliced provolone cheese; 1 small yellow onion, thinly sliced; 1 small red onion, thinly sliced; 1 small bulb fennel, cored and thinly sliced; 2 tsp. fresh thyme leaves; 1 1/2 tbsp. olive oil; Kosher salt and pepper; 2 oz. fontina cheese, coarsely grated; Finely chopped flat-leaf parsley, for sprinkling