Place all of the ingredients into a completely dry food processor or blender and pulse until it resembles small, coarse breadcrumbs. Transfer to a container and set aside.
You will only need 1/4 cup for this dish, so save the rest and top lots of other things with it throughout the week. It goes well on nearly everything.
Heat a skillet over medium - high heat for a couple minutes, and then add the mushrooms and a pinch of salt. Cook 7- 10 minutes, stirring frequently, until the mushrooms are nice and soft.
Remove half of the mushrooms and set them aside. You will be using these for the casserole.
Place the other half of the mushrooms into your blender, along with the cashews that you soaked in water earlier (be sure to drain and discard the water first), garlic, salt, pepper, thyme, sage, marjoram, nutmeg, smoked paprika, lemon juice and non-dairy milk.
Blend until super smooth. If the sauce looks too thick, add a bit more non-dairy milk to thin it out.
Make the Casserole Sauce and the Cashew Parmesan first and then come back to mama.
Did you make the Casserole Sauce and the Cashew Parmesan? If yes, continue. If no, go do that first and then come back.
Preheat the oven to 350 °F (180 °C).
Heat a skillet over medium heat for a couple minutes and then add the onions. Cook for about 7 minutes, adding a splash of water and stirring when they start to stick to the skillet or look dry. The onions should be a nice, deep brown color. When they’re nice and brown, turn off the heat and set aside for now.
Rinse the green beans and remove stem ends. Cut the beans in half or in thirds if they are exceptionally long. Place one cup of water into the bottom of a the Instant Pot, followed by the IP trivet. Place the beans on top of the trivet. Set the timer for 1 minute, using the manual (or Pressure Cooker) setting and use the quick release method when the timer is up. If you do not have an IP, simply steam the green beans on the stove top.
Place the steamed green beans on the bottom of a 2.5 quart casserole dish, followed by half of the onions, the mushrooms you reserved earlier (from the casserole sauce) and all of the Casserole Sauce. Gently stir. Add the remaining onions on top, followed by the Cashew Parmesan.
Bake uncovered for about 20 minutes, until the sauce is slightly bubbling and heated through. If the onions begin to over brown, lightly cover the casserole with foil until done.