French Onion Pasta

Instructions

1. In a large, deep skillet (or Dutch oven) with a lid, melt the butter over medium low heat. Add the onions, salt, and pepper. Cook low and slow, stirring every now and then, until the onions are deep dark brown, jammy, and ultra caramelized, about 35 to 45 minutes. You don't need to baby sit them, but pop over and stir about every 4 to 5 minutes at the beginning, then more often towards the end. If at any point the onions start to stick to the pan, add 1 tablespoon of water to loosen them (you may need to add water a couple of times).
2. Add the garlic and thyme. Cook and stir for 1 minute, until the garlic is ultra fragrant.
3. Add the white wine and sherry vinegar, then use a wooden spoon to scrape up any stuck on bits (this is called deglazing and it makes food DELISH). Let simmer while scraping for 1 minute.
4. Stir in the Worcestershire and mustard.
5. Scoot the onions to one side of the pan and add the rigatoni to the other. Pour the beef broth over the pasta; it should be mostly submerged.
6. Increase the heat to high. Once the entire surface of the pot is simmering (it took the liquid over the noodles longer than the liquid over the onions for me), cover the pot, reduce the heat a bit, and let simmer until the noodles are al dente, about 15 minutes. Every few minutes, lift up the lid and stir the noodles to keep them from sticking. Most of the liquid should absorb, but if the pasta is still very liquidy, let it simmer uncovered until the excess broth is absorbed.
7. Stir in the gruyere and Parmesan - for best results, add the gruyère a little at a time so it melts more more smoothly. Stir in the half-and-half.
8. Carefully taste and adjust the seasoning as you like. Serve hot.