Step 1: Heat 1 tablespoon olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Season the chicken pieces with salt, pepper, and 1/2 teaspoon garlic powder.
Step 2: Add chicken to the hot skillet and cook for 5-7 minutes, flipping occasionally, until golden brown and cooked through. Remove the chicken from the skillet and set aside.
Step 3: In the same skillet, melt the remaining 3 tablespoons of butter over medium heat. Add minced garlic and sauté for 1 minute until fragrant, being careful not to burn it.
Step 4: Slowly pour in the heavy cream, stirring constantly. Add the remaining 1/2 teaspoon garlic powder. Bring the cream to a gentle simmer, but do not let it boil vigorously. Reduce heat to low.
Step 5: Gradually add the freshly grated Parmesan cheese, a handful at a time, stirring continuously until each addition is fully melted and incorporated. The sauce will thicken as you add the cheese. Season with salt and black pepper to taste.
Step 6: While the sauce is simmering, cook the fettuccine according to package directions in a large pot of generously salted water until al dente. Reserve about 1 cup of pasta water before draining.
Step 7: Add the cooked chicken and drained pasta directly into the Alfredo sauce. Toss gently to coat everything evenly. If the sauce seems too thick, add a splash of reserved pasta water until it reaches your desired consistency.
Step 8: Serve immediately, garnished with fresh chopped parsley and extra grated Parmesan cheese.