Marinate the chicken with 2 teaspoon of fajita seasoning.
Boil the pasta al dente. Do it just before the sauce is ready so that you can immediately add to it. Running water/oil over pasta makes it difficult for the sauce to stick to it.
Take some oil in a pan and add the onions. When they turn translucent, add the mushrooms on high heat. And when the mushrooms begin to brown add the capsicum, jalapeno pepper and 1 teaspoon of fajita seasoning. Stir fry for 2 mins. Take out all the vegetables and keep aside.
In the same pan, add the chicken. Cook till seared and brown. Take out.
Now in that pan, heat a tablespoon of oil and add the garlic cloves. When it starts to brown, add the cream, milk and chicken cube. Let simmer for 2 mins and then add the pasta, vegetables, chicken and rest of the fajita seasoning.
Stir on medium heat till the pasta absorbs most of the cream. Then pour the pasta water to thicken the sauce.
In the end, add the cheese and mix until it melts.
Sprinkle some paprika powder before serving.
Serve with garlic bread and enjoy!
Notes
You can use any kind of pasta in place of fettuccine.