Galette Dough (Allow 1-2 hours refrigeration time or up to 3 days).

1.  Whisk flour, cornmeal and salt in a large bowl. See notes for food processor. 
2. Add the diced butter, and using a pastry cutter (or your fingers), break it apart into the flour mixer until it’s the consistency of coarse sand with flecks of butter no bigger than a pea.
3. Mix in the parmesan if using.
4. In a small bowl, whisk the sour cream and 4 tablespoons water together, then pour this into the flour mixture.  Using a wooden spoon or your hands and mix until the flour is fully incorporated. The dough should clump together and form a ball.
5. If the mixture is dry, add a tablespoon of cold water at a time, just enough to incorporate all the flour. ( The amount of water will depend on whether you are using cheese.)
6. Flatten the ball and cover it with parchment (or wrap the whole ball in parchment), refrigerating for 1-2 hours so the flour and cornmeal can fully hydrate.

Galette Filling

1. Cut and prep your veggies.
2. Heat olive oil in an extra-large saute pan over medium-high heat. Add the onions and saute for 3 minutes, stirring; add the garlic and saute for 2 minutes, stirring; add the zucchini and thyme and season with salt and pepper and optional chili flakes, and smoked paprika, and saute, stirring until tender, about 10 minutes, lowering heat if necessary.
3. Add the corn, and saute 3-4 more minutes, then add the cherry tomatoes, sauteing until just collapsing, about 3-4 minutes.
4. Increase the heat for just a few minutes to cook off any excess liquid. Turn the heat off.
5. Stir in the basil, half of the parmesan, and adjust salt and pepper to taste. 
6. Let this come to room temp- or refrigerate in an airtight container for up to 3 days.

Assemble and bake! Preheat oven to 400F (or 375F convection). 

1. Roll the dough.  Place the pie dough on a lightly floured piece of parchment paper, flatten it into a disk, and flour the top. Using a rolling pin, working from the middle out, roll out to a 14 to 15-inch round, turning the dough and flipping it over a couple of times, and adding flour to prevent sticking.  Trim the edges (using a pizza cutter) if you prefer tidy edges. Lift the dough with the parchment over to a sheet pan. 
2. Assemble. Spread the ricotta in a thin layer, leaving 2-inch border.  Sprinkle with the remaining half of parmesan. Top with the vegetable filling, spreading evenly over the ricotta- if your filling is very juicy, use a slotted spoon.  Loosen the dough border from the parchment and fold it up and over the filling, working in the same direction, creating concentric folds. The center will remain open. Brush the free-form pie crust with the egg wash to add a golden sheen. You could sprinkle the egg-washed dough with a little finishing salt. 
3. Bake. Place in the oven on the middle rack and bake until beautifully golden, 35-45 minutes. 
4. Serve warm or at room temp.