Philly Cheesesteak Mac-n-Cheese

Another goody from Rach....
Serves 6
Ingredients:
Salt
1 pound cavitappi pasta
2 tbsp. EVOO
2 large onions, thinly sliced
Black pepper
3 tbsp. butter
3 tbsp. AP flour
3 c. milk
2 c. shredded provolone
1/2 c. beef stock
3/4 c. thinly sliced roast beef, coarsely chopped
1/4 c. fresh flat leaf parsley, chopped

Place a large pot of water over high and heat and bring it to a boil. Salt the water, add the pasta, and cook to al dente. Drain the pasta and return it to the pot.
While the pasta water is coming to a boil, heat the EVOO in a large skillet over medium to medium-high heat. Add the onions, season with salt and pepper and cover with a lid or foil for 2 to 3 minutes to get them going. Remove the lid or foil and continue cooking the onions until tender and lightly caramelized, 12 to 15 minutes, stirring occasionally.

While the onions are caramelizing, melt the butter in a medium pot over medium-high heat. Sprinkly the flour over the melted butter and cook for about 1 minute, stirring constantly. Whisk the milk into the butter-flour mixture slowly and bring up to a bubble to thicken, about 5 minutes. Remove the pot from the heat and stir in 1 1/2 cups of shredded cheese, season with salt and pepper and reserve.

Preheat your broiler. Add the beef stock and the roast beef to the onions, stir over medium heat to warm through. Add the cheese sauce and the onion-roast beef mixture to the pot with the pasta and toss to comibine. Return this mixture to the pot or casserole dish and top with the remaining cheese. Place under the broiler until bubbly, 2 to 3 minutes, garnish with parsley.