Steak and Blue Cheese Mac and Cheese

Ingredients

• 3 pounds flank steak
• Salt, to taste
• Freshly ground black pepper, to taste
• 2 tablespoons olive oil
• 3 tablespoons unsalted butter
• 1 (4-ounce) container pancetta, or substitute bacon, finely chopped
• 1 medium red onion or substitute 2 large shallots, finely chopped
• 1½ teaspoon plus more for garnish, fresh thyme
• 16 ounces pasta (large macaroni, medium shells), 1 cup pasta water reserved
• 4 tablespoons all-purpose flour
• 3 cups whole milk
• 2 (5-ounce) containers Frigo® Crumbled Blue Cheese, divided
• 1 (5-ounce) container Frigo® Shredded Parmesan Cheese
• 1 cup chopped walnuts, toasted
• ½ cup freshly chopped parsley and/or chives, for garnish (optional)