French Onion Steak Pasta

Cook the Pasta
1 Bring water to a boil in a large pot over high heat. Add 1 tablespoon of kosher salt to the water once it reaches a rolling boil.
2 Add the dried linguine, and cook for 7-10 minutes. Follow the instructions on the packaging, as some will cook faster than others.
3 When the pasta is al dente, meaning it still has a bit of a bite, dip a cup into the water to reserve at least ½ cup. Drain the pasta, and then drizzle 1-2 tablespoons of olive oil onto it to prevent the pasta from clumping. Set aside for later.
Caramelize the Onion
5 Using a sharp knife or a mandoline, slice the onions into thin rounds.
6 In a nonstick skillet or a cast iron skillet over medium heat, melt the butter.
7 Add the onion to the skillet, and cook over medium heat. Stir it constantly with a wooden spoon so nothing begins to stick to the bottom of the pan.
8 This process will take 20-35 minutes, just depending on how hot your stove runs and how comfortable you feel with a higher heat setting.
9 Remove the onions from the skillet, and set aside.
Sear the Steak
11 Pat the steak dry with a paper towel, blotting it to remove excess moisture. (This will help the exterior of the steak caramelize in the pan!) Season with salt and pepper on both sides.
12 In the same skillet where you caramelized your onions, add the butter, allowing it to melt over medium-high heat.
13 Once the butter is bubbling, place the steak in the pan. You’ll hear loud sizzling noise. (If the noise isn’t loud, your pan might not be hot enough. If that’s the case, crank up the heat so you hear this sizzling.)
14 Do not touch the steak as it sears, and let it cook for 3-4 minutes before flipping with tongs and cooking for another 3-4 minutes on the other side. You will only flip the steak once!
15 Take the steak’s temperature by using an instant read thermometer. Stick it into the thickest part of the steak and read the temperature. For a medium rare steak, remove the steak at 140°F, and let it rest, uncovered, for 5-10 minutes, or until the internal temperature climbs up to 145°F.
16 Once the steak has rested and hit the temperature you like to eat your steak at, you can slice it thinly to place on top of the pasta.
Make the Sauce
18 Turn down the heat under the same skillet from all the steps above to MEDIUM.
19 Sprinkle in the flour. Stir that in with the juices and fats remaining in the pan to make a roux. This will be the thickener for our sauce, so don’t skip this step, and make sure that the flour and fat actually mix together before pouring in the liquids.
20 Pour in the beef bone broth, stirring constantly, until the mixture thickens. This could take 2-3 minutes, depending on your stovetop.
21 Next, pour in the milk, and stir the sauce as it thickens. This will take another 2-3 minutes.
22 Once the sauce is decently thick, add the cheese and thyme. Stir constantly until the cheese has melted into the sauce.
23 Add the onions back in, stirring to mix, and then add the pasta into the sauce. Add the pasta water to help the sauce stick to the cooked pasta, tossing it with tongs.
24 Serve immediately, topping with the sliced steak, and enjoy with extra gruyere and thyme leaves!