Pat the chicken tenderloins dry and season both sides with salt and black pepper. Place the flour in a shallow bowl and season lightly with salt and pepper. In a second shallow bowl, whisk together the eggs, 2 tablespoons fresh parsley, crushed red pepper flakes, zest of half a lemon, and a little salt and pepper.
Dredge each chicken tenderloin in the seasoned flour first, shaking off any excess. Then dip it into the egg mixture, coating both sides.
Heat 4 tablespoons salted butter and 1 tablespoon olive oil in a large skillet over medium to medium-low heat. Add the chicken directly to the skillet after dipping it in the egg mixture. Cook for about 5 minutes without disturbing it. Once the chicken naturally releases from the pan and is golden brown, flip and cook for about another 5 minutes. Reduce the heat to low as needed and continue cooking until the chicken reaches an internal temperature of 165°F.
Remove the chicken from the skillet and set aside. Do not clean the skillet! Leave all of those delicious buttery chicken drippings right in there.
Bring a large pot of salted water to a boil. Cook 12–16 ounces of fettuccine or pappardelle until about 1–2 minutes shy of al dente. Before draining, reserve at least 1 cup of pasta water.
While the pasta cooks, add the sliced red bell pepper, green bell pepper, optional yellow bell pepper, sliced red onion, and sliced garlic directly to the skillet with the chicken drippings. Season with Italian seasoning, onion powder, black pepper, and a little salt to taste. Sauté over medium to medium-low heat until the vegetables are softened, golden, and translucent.
Pour in the Chardonnay and scrape up all the browned bits from the bottom of the skillet. Let the wine simmer over low heat for about 3–5 minutes so it can reduce slightly.
Pour in the heavy cream and about ½ cup of the reserved pasta water. Bring the sauce just to a boil, then immediately reduce the heat to a gentle simmer. Let it cook until the sauce begins to thicken.
Add the remaining lemon zest and the juice of about half a lemon. Stir in about ½ cup freshly grated Pecorino Romano. Taste and adjust with additional salt, black pepper, lemon juice, crushed red pepper flakes, or Pecorino Romano as needed.
Add the pasta directly to the skillet and toss until completely coated in the creamy scampi sauce. Add additional reserved pasta water, a little at a time, if needed to loosen the sauce.
Finish with fresh parsley, crushed red pepper flakes, and additional Pecorino Romano. Nestle the chicken over the pasta and serve immediately with extra Pecorino Romano on top.