# Components:
→ Vegetables
01 - 2 large yellow onions, thinly sliced
02 - 1 medium head green cabbage (about 3.3 lbs), cored and shredded
→ Dairy
03 - 3 tablespoons unsalted butter
04 - 1 cup heavy cream
05 - 1 cup whole milk
06 - 1½ cups grated Gruyère cheese, divided
07 - ½ cup grated Parmesan cheese
→ Other
08 - 2 tablespoons olive oil
09 - 2 cloves garlic, minced
10 - 1 teaspoon fresh thyme leaves or ½ teaspoon dried
11 - ¼ teaspoon freshly grated nutmeg
12 - Salt and freshly ground black pepper, to taste
13 - ½ cup gluten-free breadcrumbs
# Directions:
01 - Preheat oven to 375°F. Grease a 2-quart baking dish with butter or oil.
02 - Heat butter and olive oil in a large skillet over medium heat. Add sliced onions and cook, stirring occasionally, until caramelized and golden brown, approximately 18 to 22 minutes.
03 - Stir in minced garlic and thyme leaves; cook for 1 minute. Add shredded cabbage and cook, stirring often, until wilted and lightly browned, about 10 minutes.
04 - Season the mixture with salt, pepper, and nutmeg. Remove from heat.
05 - In a saucepan, gently heat heavy cream and whole milk over low heat until warmed through.
06 - Add half of the Gruyère and all Parmesan cheese to the warmed cream mixture. Stir continuously until cheeses are fully melted and sauce is smooth. Adjust seasoning if needed.
07 - Fold the caramelized onion and cabbage mixture into the cheese sauce. Transfer the combined mixture evenly into the prepared baking dish.
08 - Sprinkle remaining Gruyère and gluten-free breadcrumbs evenly over the top.
09 - Bake in preheated oven for 25 to 30 minutes, or until the top is golden brown and bubbling.
10 - Allow gratin to rest for 5 to 10 minutes before serving to set.
