French Onion Chicken Mac Cheese - Zest Plate

Ingredients

• 2 medium yellow onions, diced
• 2 tablespoons olive oil
• 2 tablespoons unsalted butter
• 1 teaspoon sea salt
• 1/2 teaspoon ground black pepper
• 16 ounces elbow macaroni, cooked al dente and drained
• 113 grams unsalted butter
• 62 1/2 grams all-purpose flour
• 490 grams whole milk, warmed
• 240 grams beef stock
• 2 teaspoons kosher salt
• 1/2 teaspoon ground mustard powder
• 1/4 teaspoon garlic powder
• 1/4 teaspoon cayenne pepper (optional)
• 113 grams sharp Gruyère cheese, freshly shredded
• 56 1/2 grams mozzarella cheese, freshly shredded
• 280 grams shredded rotisserie chicken
• Salt and ground black pepper, to taste
• 28 grams Gruyère cheese, shredded
• Fresh thyme, chopped for garnish