Filling Ingredients:
2 tbsp. olive oil
1 large white onion, diced
salt and freshly ground black pepper
2 cloves garlic, chopped finely
1 tbsp. marjoram, chopped
kernels from 1 ear of corn (about 1 cup)
1 recipe Cornmeal Galette Dough (see below- make ahead)
1 large or 2 medium ripe tomatoes (about ¾ lb. Total) cut into 1/3-inch slices, drained on paper towels
3 oz. Italian Fontina, shredded
1 large egg yolk mixed with 1 tsp. milk or cream

Dough Ingredients:
Yields enough dough for 1 galette about 11 inches in diameter; recipe can be doubled.
1 ¼ cups all-purpose flour
1/3 cup fine yellow cornmeal
1 tsp. sugar
1 ¼ tsp. salt
1 tsp. freshly ground black pepper
1/3 cup grated Parmesan cheese
6 tbsp. unsalted butter, cut into ½-inch pieces and chilled
3 tbsp. olive oil
¼ cup ice water

Heat the olive oil in a sauté pan, preferably nonstick, over medium heat. Add the onion and cook, stirring frequently, until lightly browned, about 10 minutes. Season with salt and pepper. Add the garlic, marjoram, and corn and cook for 30 seconds. Transfer the mixture to a bowl and set aside to cool.

Pre-heat the oven to 375ºF. Line a baking sheet with kitchen parchment.

Roll the dough on a floured surface into a 15-inch round, lifting the dough with a metal spatula as you roll to make sure it’s not sticking. If it is, dust the surface with more flour. Transfer it by rolling it around the rolling pin and unrolling it on the lined baking sheet.
Spread the onion and corn mixture over the dough, leaving a 2-inch border without filling. Arrange the tomatoes in a single layer over the onions and season them with salt and pepper. Sprinkle the cheese over the tomatoes. Lift the edges of the dough and fold them inward over the filling, pleating as you go, to form a folded-over border. Pinch together any tears in the dough. Brush the egg yolk and milk mixture over the exposed crust.
Bake until the crust has browned and the cheese has melted, 35 to 45 minutes. Slide the galette off the parchment and on to a cooling rack. Let cool for 10 minutes before serving.

In a medium bowl, mix together the flour, cornmeal, sugar, salt, pepper, and Parmesan cheese. Cut in the chilled butter using a stand mixer, a food processor, or a pastry blender until it’s evenly distributed but still in large, visible pieces. Add the olive oil and ice water and mix until the dough begins to come together. Gather the dough with your hands and shape it into a disk. Wrap the disk in plastic and refrigerate for at least 1 hour.