Place the chicken in a mixing bowl. Sprinkle it with the salt and pepper. Add just 2 tablespoons of the flour and toss to coat again. Set aside.
Prep the veggies and set aside.
Boil the pasta according to the package directions. I always use the lowest time listed on the box so the pasta is very firm and can soften up in the pasta sauce. Drain and set aside.
Place a large skillet over medium-high heat. Add just 2 tablespoons of the butter and all of the olive oil. Let the butter melt. Once it is bubbling, use a fork to shake off any excess flour from each chicken tenderloin and place them in a single layer in the skillet. Cook for 4 minutes on the first side and then flip the chicken over. Cook for an additional 4 minutes on the other side. Transfer the chicken to a clean plate and set aside.
Add the additional 2 tablespoons of butter to the no-empty pan. Once it has melted, add the sliced bell peppers and onion. Stir and cook for 3 - 5 minutes or until the peppers are just beginning to soften. Use a slotted spoon to transfer the vegetables to the same plate the chicken is resting on.
Add the minced garlic to the pan and stir for 30 seconds. Add the remaining 2 tablespoons of flour to the pan and whisk it into the butter for 20 - 30 seconds.
Pour in the chicken broth and whisk it into the flour. Add the red pepper flakes and Italian seasoning to the pan. Reduce the heat to medium and let it simmer for 10 minutes.
Add the lemon juice and heavy cream to the skillet and stir it into the sauce.
Transfer the peppers and chicken back to the pan. Stir them into the sauce and let them warm up again for 2 - 3 minutes.
Add the pasta to the pan and use the tongs to gently toss the pasta in the sauce. Cover the skillet and let the pasta heat through for 2 minutes. Serve immediately.