# What You'll Need:
→ Pasta
01 - 12 ounces rigatoni or penne
→ Onions
02 - 3 large yellow onions, thinly sliced
03 - 2 tablespoons unsalted butter
04 - 1 tablespoon olive oil
05 - 1/2 teaspoon fine salt
06 - 1/4 teaspoon freshly ground black pepper
07 - 1 teaspoon granulated sugar
08 - 2 garlic cloves, minced
09 - 1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried)
→ Sauce & assembly
10 - 1/2 cup dry white wine
11 - 2 cups vegetable broth
12 - 2 teaspoons Worcestershire sauce
13 - 1 tablespoon all-purpose flour
14 - 1 cup heavy cream
15 - 1 1/2 cups grated Gruyère, divided
16 - 1/2 cup grated Parmesan
17 - 1 tablespoon chopped fresh parsley (for garnish)
# Step-by-Step Guide:
01 - Preheat oven to 400°F and grease a 9x13-inch baking dish.
02 - Bring a large pot of salted water to a boil, cook the pasta until just short of al dente, drain and set aside.
03 - Heat butter and olive oil in a large skillet over medium heat; add sliced onions, salt, pepper and sugar, and cook, stirring frequently, until deep golden brown and caramelized, about 25–30 minutes.
04 - Stir in minced garlic and thyme and cook for 1 minute until fragrant.
05 - Sprinkle the flour over the onions, cook 1 minute, pour in the white wine while scraping up browned bits, and simmer 2 minutes.
06 - Add the vegetable broth and Worcestershire sauce, bring to a simmer and cook for 2–3 minutes to meld flavors.
07 - Reduce heat to low, stir in the heavy cream and 1 cup of the grated Gruyère until the cheese melts and the sauce is smooth.
08 - Add the drained pasta and the Parmesan to the skillet, toss gently to coat evenly with the sauce.
09 - Transfer the pasta mixture to the prepared baking dish and sprinkle the remaining Gruyère evenly over the top.
10 - Bake in the preheated oven for 20–25 minutes, until the top is bubbly and golden brown.
11 - Let rest a few minutes, garnish with chopped parsley and serve warm.
