Wash zucchinis and chop off the ends. Make zucchini pasta using spiralizer, mandoline or vegetable peeler, and then set aside.
Melt butter in a medium saucepan over low heat.
Stir in flour and whisk constantly. Cook for about 2 minutes, but don't brown.
Stir in oat milk gradually, constantly stirring. Cook over low heat until sauce begins to thicken.
Stir in minced garlic, Italian seasoning, nutritional yeast, salt, and black pepper to taste, and cook for few more minutes. Remove from heat.
Toss the zucchini pasta into the mixture and stir until the pasta is coated evenly.
Serve topped with parsley.