This dish is based on traditional au gratin potatoes, but without the cheese, milk, butter or flour. And along with the potatoes, thin layers of mushrooms and onions are stacked with chard and fresh basil. A few cashews make the sauce rich and creamy.
In a high-speed blender, grind the cashews by themselves first; then add the water, soy milk, parsley, green onions and garlic powder and blend thoroughly. Set aside.
To prepare the vegetables, using a mandolin slicer with the thin slicing blade (as if you were making potato chips), slice the potatoes, mushrooms and onion, and set aside in separate bowls. Remove the thickest stems from the chard leaves, and rough chop the basil; wash both and set aside.
In a 13”x9” rectangular glass baking dish, layer vegetables in this order, starting with a thin layer of sauce in the bottom of the dish (you do not need to oil or prepare the pan): potatoes, mushrooms, onions, basil, chard, sauce. Add a second layer of vegetables and sauce, then finish with a final layer of potatoes, pouring the last bit of sauce over the top. Cover with aluminum foil and bake at 400 degrees for 35 minutes. Remove the foil and cook an additional 15 minutes until lightly browned (optional: grind some cashews on top first). Remove and let sit for at least 5 minutes before serving.
Don’t be afraid to pile the vegetables high when making your layers, as everything will condense down quite a bit while cooking. If you don’t have a high-speed blender (like a Vitamix or Tribest personal blender), you may use a standard blender; just soak the cashews in the 1 cup of water for about 15 minutes first. If there are small cashew pieces in your sauce, no worries, it will still work fine.
For a lower fat dish, leave the cashews off and decrease the water by ½ cup. The layers will not stick together as well, but the flavor will still be great. If you do not have a mandolin, just slice the vegetables by hand as thinly as you can. This dish makes great leftovers.