Butter, for greasing the pan
2 cups marinara or tomato-basil sauce
1 cup Arborio rice
3 tablespoons unsalted butter, at room temperature
1/4 cup all-purpose flour
1 1/4 cups whole milk, at room temperature
1/4 teaspoon kosher salt
1/8 teaspoon ground nutmeg
1/2 cup plus 1/3 cup grated Parmesan
4 ounces thinly sliced prosciutto, coarsely chopped
1 cup frozen peas, thawed
4 large eggs, at room temperature, beaten
1/2 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
1/3 cup plain breadcrumbs