Season chicken breast with salt and pepper. Heat a cast-iron skillet over medium-high heat. Add oil and once hot, add chicken breast. Cook 3-5 minutes per side (depending on thickness) or until cooked through. Set aside.
Add onion and garlic to skillet and sauté until fragrant. Add diced tomatoes, tomato sauce, coconut milk, vodka, tomato paste, Italian seasoning, and red pepper flakes. Lower heat and simmer uncovered for 20 minutes.
Remove sauce from heat and add nutritional yeast, spinach, and about two thirds of the chopped basil to the sauce. Stir until spinach is softened into the sauce. Set aside.
Cook gluten-free pasta until al dente if serving immediately or very al dente if using in meal prep (I removed mine from boiling water at just under 5 minutes). Run under cold water to stop cooking, then toss with pasta sauce and divide evenly into 4 servings. Top with sliced chicken.