Cook pasta according to package instructions.
Add 2 tbsp avocado oil to a large skillet or fry pan over low-medium heat. Add in minced garlic and diced onion and cook until onions are translucent.
Whisk the cornstarch with one cup of almond milk until it dissolves and add it into the skillet. Add butter and season with salt and pepper. Mix. Once this has thickened up a bit add the remaining almond milk.
In a blender or food processor add in the above mixture along with 1/2 cup of sun-dried tomatoes, nutritional yeast, and water. Blend until smooth and creamy. Add more water as needed by the tablespoon. You want it on the thicker side not too runny.
Add another 1 to 2 tbsp avocado oil in the same frying pan. Add in the other 1/2 cup of the sun-dried tomatoes, and sliced mushrooms and cook for 5 minutes.
Pour the sauce from the blender back into the pan with the whole sun-dried tomatoes and mushrooms on low heat. Once the sauce is heated a bit add in the penne, spinach, and basil, more salt and pepper if desired and give it a good mix. Once the spinach is a bit wilted it's good to go.
Serve right away and sprinkle the top with vegan parmesan and extra chopped fresh basil and great with a side salad. Enjoy!