Bring a pot of salted water to a boil and cook the fettuccine according to package directions until al dente, reserving 1/4 cup of pasta water before draining.
While pasta cooks, season the chicken breast with sea salt, black pepper, and onion powder.
Heat the olive oil in a large skillet over medium heat and sauté the chicken until golden brown and cooked through, about 5-6 minutes per side.
Remove chicken from the skillet to rest, then add the minced garlic to the same pan, sautéing for 30 seconds until fragrant.
Steam the broccoli florets until tender-crisp, about 3-4 minutes.
In a small bowl, whisk together the Greek yogurt, grated parmesan, and the reserved warm pasta water until smooth.
Slice the chicken into strips and add it back to the skillet along with the cooked pasta, steamed broccoli, and the yogurt sauce.
Toss everything together over low heat until the sauce is creamy and coats the pasta evenly, then garnish with fresh parsley.