Cauliflower and Ham Crustless Quiche

Name: Cauliflower and Ham Crustless Quiche
Ingredients: 1/2 head cauliflower, cut into bite-size florets; 2 tablespoons extra-virgin olive oil; 1 cup chopped white onion, about 1 medium; 2 tablespoons chopped flat-leaf parsley; 4 ounces deli boiled ham, cut in 1/4-inch cubes; 2 tablespoons unsalted butter, softened; 2 tablespoons finely grated Parmesan cheese; 2 cups half-and-half; 2 large eggs; 2 large egg yolks; 1 tablespoon all-purpose flour; 1/2 teaspoon kosher salt; Freshly ground black pepper; 4 ounces grated Gruyere or Swiss cheese, about 1 cup