Cook pasta according to package directions.
Drain, rinse with cold water and set aside.
Using a large pan or skillet, melt 2 tbsp butter over medium heat.
Add chicken and sprinkle with Italian seasoning, garlic salt, pepper and slap ya mama. Stir.
Cook chicken until almost thoroughly cooked, then add onions and mushrooms.
Continue cooking until chicken is no longer pink and onions and mushrooms are tender.
Add remaining butter and garlic. Saute for 2 additional minutes, stirring frequently.
Pour in heavy cream, stir, lower heat and simmer.
Add ½ of the Parmesan cheese and all of the cream cheese. Constantly whisk until cheese is fully incorporated.
Add the remaining Parmesan and whisk continuously until the cheese is fully melted and mixed well.
Reduce heat and let simmer for 10 minutes stirring occasionally.
Add fettuccine pasta to the sauce mixture and stir.
Serve immediately.