Mac and Cheese Primavera

Name: Mac and Cheese Primavera
Ingredients: 1 pound medium pasta shells; 2 tablespoons salted butter; 2 tablespoons olive oil; 1 cup small broccoli florets; 2 scallions, sliced, whites and green parts separated; 2 cloves garlic, minced; 1 bunch asparagus, cut into 2-inch pieces; 1 small red bell pepper, diced; 1 teaspoon kosher salt; 1/2 teaspoon freshly ground black pepper; 1/2 cup dry white wine; 2 cups whole milk; 1/2 cup heavy cream; 1 cup frozen peas; 1 cup shredded fontina cheese; 1 cup shredded white Cheddar; 2 teaspoons cornstarch