Caramelized Onion & Cheddar-Brie Mac and Cheese

A cozy, elevated twist on mac and cheese: buttered penne layered over a silky aged cheddar-Brie sauce, folded with caramelized onions, and finished with fresh Serrano heat. Even my picky daughter said, “Yum, that’s good!”

Aug 26, 2025

Butter-Tossed Penne with Cheddar-Brie Fonduta, Caramelized Onions & Serrano Heat

Like most kids, mine love mac and cheese. It’s the one dish I know will always bring them to the table. But I had some leftover high-quality aged New York cheddar in the fridge, and I wanted to make something that wasn’t just for them — I wanted a version that my wife and I could love just as much.
Some nights, it’s the little things that make all the difference. That cheddar was sharp and crumbly, begging to be turned into something comforting. I melted it into a silky sauce with Brie, folded in caramelized onions I had stashed away, and served it as a pool under buttered penne. The buttery pasta helps mop up the cheese sauce, and with a little Brie folded in for extra creaminess, it turned into a dish that felt both cozy and elevated. This one’s a keeper. For the grown-ups, I finished it with slices of fresh Serrano for heat.
The real highlight, though, came before dinner even hit the table. My daughter, who is by far the pickiest eater in our house, dipped a spoon into the sauce, gave it a taste, and said:
“Yum, that’s good!”
She’s not one to hand out compliments lightly, so that three-word review made my whole day.

Ingredients

  • 10 oz aged New York cheddar, finely grated
  • 3–4 oz leftover Brie, grated or chopped
  • 16 oz penne pasta
  • 4 tbsp salted Kerrygold butter (for sauce)
  • 3 tbsp all-purpose flour
  • 2 1/2 cups whole milk, warmed
  • 1/2 cup heavy cream (optional)
  • 1 Tblsp Dijon mustard
  • 2/3 cup chopped caramelized onions (folded into sauce)
  • 4 tbsp salted Kerrygold butter (for tossing pasta)
  • 1 fresh Serrano chile, thinly sliced (for garnish, adults only)
  • Salt & black pepper, to taste

Method

  1. Make the fonduta
    1. Melt 4 tbsp butter in a saucepan, whisk in flour, and cook 1–2 minutes.
      Slowly whisk in warm milk + cream until smooth. Simmer until slightly thickened.
      Off the heat, stir in cheddar + Brie until melted and silky. Stir in caramelized onions. Season with Dijon, salt, and pepper. Keep warm on very low.
  1. Cook pasta
    1. Boil penne in salted water until al dente. Drain, reserving 1/2 cup pasta water.
      Toss pasta with 4 tbsp butter, the pasta water and a spoonful or two of sauce — just enough to coat lightly.
  1. Assemble
    1. Spoon a generous pool of cheddar-Brie fonduta into each serving bowl.
      Pile buttered pasta on top.
      Finish adult portions with fresh Serrano slices for heat.
      Optional: finish with crunchy Panko bread crumbs that have been toasted in EVOO.

Dinner went over beautifully — the cheddar and Brie gave the sauce just the right mix of sharpness and creaminess, the onions brought sweetness, and the Serrano kept the adult portions lively. But the best part wasn’t the plating or the flavors, it was what came out of my daughter’s mouth on her second taste:
“It tastes like deep fried bacon, and I’ve never even tried deep fried bacon.”
I couldn’t have described it better myself.

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