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French Onion Mac and Cheese

PREP TIME 15 minutes
COOK TIME 45 minutes
TOTAL TIME 1 hour
servings4 servings
This one-pot French Onion Mac and Cheese is made on the stovetop, where the pasta cooks right in the sauce with caramelized onions and milk for a deep, creamy flavor.
Bowl of creamy French onion mac and cheese topped with caramelized onions and thyme, on a neutral napkin.
Ingredients
  • 2 Tablespoons (30 g) butter
  • 1 teaspoon (5 g) olive oil (can use canola or sunflower oil)
  • 2½ medium onions (about 500 g, sliced medium - thick)
  • 1 teaspoon (5 g) sugar
  • 1 teaspoon dried thyme (or a few fresh sprigs)
  • 2½ Tablespoon (20 g) all-purpose flour
  • 2½ cups (600 ml) milk (see note 1)
  • 1½ cups (375 ml) water
  • 2½ cups (250g) uncooked macaroni or short pasta
  • 1 cup (100 g) shredded cheese (Cheddar, mozzarella, or a mix)
  • 1½ teaspoon fine salt
  • ¼ teaspoon black pepper (or to taste)
Instructions

Times are included to help you follow each step, especially for caramelizing. Use them as a guide, not a rule.

    Caramelize onions – 25 to 30 minutes

    • In a deep pot, melt the butter and olive oil over low heat. (see note 2)
    • Add the sliced onions, sugar, and thyme. Cook gently for 20–25 minutes, stirring often, until golden and soft. Don’t be tempted to raise the heat. Slow cooking brings out the sweetness and rich flavor.
      (see note 2 below if planning to make ahead onions)
    • Scoop out 2 Tablespoons (30 g) of the caramelized onions and set aside for garnish.

    Add the flour – 1 minute

    • Sprinkle the flour over the onions and stir for 1 minute to coat evenly. This forms the base that thickens the sauce.

    Add milk, water, and pasta – 12 minutes

    • Pour in the milk, stirring for 1 minute to blend with the onions and flour. Add the water and stir gently for another minute to warm through.
    • Add the uncooked pasta and salt. Keep the heat medium and steady, there’s no need to bring it to a boil.
    • Stir lightly in the first minute to prevent sticking, then every 3–4 minutes as it cooks. Cook for about 10–12 minutes, until the pasta is tender and the sauce looks smooth and slightly glossy. It will thicken a bit more as it stands.

    Add the cheese – 2 minutes

    • Take the pot off the heat and stir in the shredded cheese until melted and creamy. Taste and add a little more salt only if needed, some cheeses are already quite salty.
    • Serve warm: The sauce will stay creamy even as it cools. Top each serving with the reserved caramelized onions.

    Storage and reheating

    • Store leftovers in an airtight container in the fridge for up to 3 days. The sauce stays creamy even after cooling.
    • Add 1–2 Tablespoons of milk per serving to bring back the silky texture. Reheat gently on low heat or in the microwave on medium, stirring halfway through. Avoid high heat, it can make the sauce too thick.
    Recipe Notes
    1. Milk: If using low-fat or long-life milk, add about 1 teaspoon olive oil, plus ¼ cup extra cheese at the end to keep the sauce smooth and creamy.
    2. Make-Ahead Caramelized Onions:  Caramelizing the onions takes about 20–30 minutes on low heat with gentle stirring for a golden color and deep flavor. Don’t rush this step or turn the heat up, slow cooking gives them sweetness and depth. You can prepare the onions a day ahead to save time later. Once cooled, store in an airtight container in the fridge. When ready to cook, melt 1 teaspoon of butter in the pot, warm the onions through, then continue with the recipe.
    See post above for:
    Nutrition
    Serving: 1serving | Calories: 558kcal | Carbohydrates: 68g | Protein: 21g | Fat: 22g | Saturated Fat: 12g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 5g | Trans Fat: 0.2g | Cholesterol: 62mg | Sodium: 1171mg | Potassium: 509mg | Fiber: 4g | Sugar: 13g | Calcium: 425mg | Iron: 1mg