Preheat oven to 400 degrees F.Directions if using a high-powered blender (like a Vitamix or Blendtec):Place steamed yellow squash, raw cashews, wine, water, tapioca flour, nutritional yeast, miso, lemon juice, salt and xanthan gum in a high-powered blender. Start on low and turn up to high speed. Blend on high speed for 5 minutes until thick, hot and creamy. After about 5 minutes, the base of the sauce will begin to cook, steam and thicken. Use the pusher to mix the sauce, while the blender is still on high, for at least another 2 minutes until the sauce gets very thick, stretchy, hot and gooey. (Blending sauce in a Vitamix for at least 5 minutes allows the sauce to heat up so much that it boils and thickens, eliminating the need to cook in a separate pan.) Set aside.In a large nonstick skillet, sauté onion over medium heat for 7-8 minutes until translucent and golden, adding a few tablespoons of water as needed to prevent sticking. Add garlic and sauté for another 2-3 minutes. Remove from heat and stir in spinach, artichokes and sauce. Season to taste with freshly ground black pepper. Pour into oven safe dish. Bake for 10 minutes until warmed through. Place dish under broiler for 2-3 minutes to make top golden and bubbly.Directions if using a standard blender:Place steamed yellow squash, soaked and drained raw cashews, wine, water, tapioca flour, nutritional yeast, miso, lemon juice, salt and xanthan gum in blender. Blend on high until smooth and creamy, stopping to scrape down pitcher as necessary.In a large nonstick skillet, sauté onion over medium heat for 7-8 minutes until translucent and golden, adding a few tablespoons of water as needed to prevent sticking. Add garlic and sauté another 2-3 minutes.Add sauce to skillet with onions and whisk over medium heat for 5-7 minutes until sauce gets thick, stretchy and gooey. (When making sauce in standard blender, it needs to be cooked to a boil in order to thicken).Remove skillet from heat and stir in spinach and artichokes. Season to taste with freshly ground black pepper. Pour into oven safe dish. Bake for 10 minutes until warmed through. Place dish under broiler for 2-3 minutes to make top golden and bubbly.