Heat a large pot of water over high heat until boiling. Salt the water to your preference and add the pasta. Cook until just shy of al dente (the pasta will finish cooking in the sauce later). Save 1 cup of the pasta water. Drain the pasta and set aside.
Make the Scampi Sauce
While the water is heating, make your sauce. Heat a medium saucepan over medium heat. Add 2 Tablespoons of butter until melted.
Add the onion and garlic to the butter and cook until just soft but not brown, approximately 3 minutes.
Add the white wine and simmer to burn off some of the alcohol and reduce 2 minutes. Scrape up any bits from the bottom of the pot while simmering.
Add the chicken stock, lemon juice, parsley, and crushed red pepper. Simmer 5 minutes.
Remove the sauce from the heat and whisk in the remaining 8 Tablespoons (1/4 stick) of butter until incorporated. Set aside.
Vegetables and Assembly
Put the large pot from the pasta back on the stove (or a new large pot - but one less thing to clean!). Add 1 Tablespoon of oil and heat over medium heat.
Once hot, add the peppers and onion and cook until just beginning to soften, approximately 3-5 minutes.
Add the sauce into the pot with the shrimp. Cook until the shrimp are cooked through (time will vary with size). They are done when they are pink, starting to curl, and looks white not gray along the back (side edge). Season the sauce to taste with salt and pepper.
Add the pasta to the pot (see note). Gently toss to coat and combine (be very gentle to help prevent the pasta from breaking - once the pasta meets the warm sauce, it will start to loosen up and unstick). Use the pasta water if needed to loosen the sauce and make it saucier as desired.
Serve the pasta in one large dish or as individual portions.
There are a lot of parts to this recipe, but many of them can be done at the same time. You can also make the sauce in advance for an even easier meal.