Mix blackening spices together in a shallow dish.
Heat a frying pan over medium-high heat. Pat chicken dry and spread blackening spice mix evenly over both sides of chicken pieces, until coated. Place in hot, ungreased pan. Cook on each side until spices are blackened and fragrant and chicken is cooked through, about 5-6 minutes total. Set chicken aside on a plate.
Bring a large pot of salted water to a boil over high heat. Cook fettuccine until al dente, 12 minutes (or according to package directions). Drain.
While pasta is cooking, wipe out frying pan used for chicken. Turn heat to medium and add olive oil and garlic to the pan. Cook garlic until fragrant, but not brown, 1-2 minutes. Add half-and-half and turn heat down to medium-low. Simmer and allow to reduce, 8-10 minutes.
Slice chicken on the bias.
To the sauce, add sun-dried tomatoes and chicken, and 1/2c of parmesan cheese. Stir until cheese is melted. Salt to taste. Add hot noodles to sauce, combine. Plate and top with green onions and more parmesan cheese.