Heat a skillet over medium-high heat and drizzle with olive oil. Season the chicken breasts with salt, pepper, and onion powder. Cook chicken 5-7 minutes in each side, or until you get a good sear on both sides and the chicken is cooked through. Set aside to cool.
Cook the fettuccine according to package instructions to al dente.
Place a medium sauce pot over medium heat, and add the olive oil and garlic. Cook until fragrant, about 1 minute. Then add the white wine, half & half, and season with salt and pepper. Bring to a simmer and reduce heat to low. Add cheeses and stir with a whisk until it all melts in. Continue cooking and storing the sauce until it thickens.
Toss the cooked fettuccine with the sauce. Serve topped with sliced chicken.