Preheat the oven to 475°F with a rack in the bottom position. Place a large rimmed baking sheet upside down on the rack to preheat, 8 minutes.
On a piece of parchment paper dusted with cornmeal, using a lightly floured rolling pin, roll pizza dough into a large circle, about 1?4 inch thick. In a large bowl, season tomatoes with salt and pepper, drizzle with oil and use hands to crush together. Add squash, garlic and chilies and toss to combine.
Scatter prepared dough with squash, spreading it out in a thin layer. Sprinkle cheese over top of pizza.
Carefully remove the hot baking sheet from the oven and slide the parchment with the dough onto it. Bake until the dough is golden and crisp, 8 to 10 minutes
Before serving, scatter basil over pizza and squeeze fresh lemon over top.
Serve immediately with salad, if desired.