Vegetable Au Gratin Casserole With Oregano-Bean Puree
[Vegan]

To Make the Casserole:

1. Preheat the oven to 425°F. Heat the oil in a 12-inch oven-safe skillet. Add the flour garlic, bay, oregano, salt, and black pepper. Cook until fragrant. Slowly add the milk, whisking constantly to avoid lumps. Add about 8 grates of fresh nutmeg. Bring to a simmer and add the potatoes.
2. Stir the potatoes around in the sauce to ensure all slices of potatoes are coated. Simmer the potatoes for about 4 minutes.
3. Add the spinach and stir to wilt. Add the onions in a single layer. Add the squash slices as the last layer. Gently press on the squash to bubble up the sauce over the slices. Cover the skillet tightly with a lid or foil and bake for 40 minutes.
4. Add the bread to a food processor and process into crumbs. Add to the casserole, spray with oil and continue to bake, uncovered, until golden, about 15 minutes. Remove from heat and set aside for 15 minutes. Serve, reserving 1/6 of the casserole.

To Make the Dressing:

1. While the casserole is baking, combine the sour cream broth, vinegar, tahini, garlic, paprika, and salt in a small blender. Process until smooth. Serve with green salad.

To Make the Purée:

1. Heat the oil in a small skillet over medium heat. Add the beans, garlic, and oregano, and sauté until the beans are fragrant, about 5 minutes.
2. Transfer the bean mixture to a food processor. Add the casserole mixture and process until as smooth as you like. Taste and adjust seasoning. Serve with crostini (toasted slices of French or Italian bread).