Start by placing the cashews in a bowl and covering them with boiling water. Set aside to soften.
Preheat the oven to 400 degrees. Dice the potatoes and carrots into small bite-sized pieces. Then transfer to a lined baking tray along with the unpeeled, whole garlic cloves. Drizzle with 1 tbsp of olive oil and season with 1/4 tsp of kosher salt. Toss to coat evenly and then spread the veggies into a single layer for even roasting.Bake for 15 minutes or until golden brown around the edges and fork-tender in the centers.
In the meantime, chop the mushrooms and set them aside. Then cut the sourdough into 1 inch cubes and set aside too. Add the remaining 2 tbsp of olive oil to a large frying pan and set to medium-high.
Once warm, add the mushrooms and let sit undisturbed for 3-4 minutes to brown. Reduce the heat to med and add the rosemary and 1/4 tsp kosher salt. Cook for another 1-2 minutes.
Deglaze the pan with 1/3 cup white wine and simmer until all but 1 tbsp of liquid is evaporated. Next add the chickpeas, frozen peas, corn, and spinach. Sauté on low heat, stirring occasionally. Cook for 3-4 minutes, then turn off the heat and set aside.
Remove the veggies from the oven and set the garlic cloves to the side. Add the potatoes and carrots to the frying pan with the veggies and chickpeas.