Combine Ingredients: Add the pasta nests to a large skillet along with the French onion soup, chicken broth, heavy cream, and Boursin cheese. Ensure all pasta is submerged in liquid for even cooking.
Bring to Boil: Cover the skillet and bring the mixture to a boil over medium-high heat. Watch carefully to prevent boiling over, which can happen quickly with dairy-based liquids.
Simmer Until Tender: Once boiling, reduce the heat to a simmer and continue cooking for 10-15 minutes until the pasta is tender. Stir occasionally to prevent sticking and to help the cheese melt evenly into the sauce.
Season and Finish: Taste and season with salt and pepper as needed. The soup and cheeses contain salt, so adjust carefully. Top the pasta with shredded Gruyere cheese, then cover again to allow the cheese to melt completely, about 2-3 minutes.