3 pounds butternut squash—peeled, seeded and cut into 1/2-inch dice
2 tablespoons extra-virgin olive oil
2 tablespoons finely chopped thyme leaves
Kosher salt and freshly ground pepper
1 tablespoon unsalted butter
3 leeks—white and light green parts only, halved lengthwise and thinly sliced crosswise (about 4 cups)
6 large eggs
2 1/2 cups half-and-half
1/4 cup freshly grated Parmigiano-Reggiano cheese
8 ounces baguette, crusts removed and bread cut into 1/2-inch dice
4 ounces thinly-sliced prosciutto, cut into thin strips