Boil pasta in salted water according to package directions. Drain and set aside.
Season chicken with garlic powder, paprika, salt, and pepper. Heat olive oil in a skillet and cook chicken 5–6 minutes per side until golden and cooked through. Remove and slice.
In the same skillet, add olive oil or dairy-free butter and sauté garlic until fragrant. Whisk in starch, then slowly add plant milk while whisking.
Stir in nutritional yeast, salt, and pepper. Simmer on low 4–5 minutes until creamy. Add lemon juice if using.
Add pasta and sliced chicken back to skillet and toss to coat evenly.
Garnish with herbs or red pepper flakes and serve warm.