Mushroom and Spinach Strata

I have never made a strata before, or heard of one. But apparently it is traditionally a layered bread casserole with an eggy custard holding it together. Tofu took on the role of the "eggy" part.

6 slices stale bread, cut into 2" pieces (toast them in the oven if they are fresh)
1 1/2 cups shallots (5 or 6 big ones)
3 T olive oil
8 oz cremini mushrooms, sliced
3 cloves garlic, minced
2 t dried thyme
1 t dried rosemary
1 t dried oregano
1/2 t crushed red pepper
several pinches of fresh ground pepper
1 t salt
10 oz fresh spinach

For the custard:
1 lb soft tofu
2 T fresh lemon juice
2 t yellow mustard
1 T arrowroot
1/2 cup veggie broth
1/4 t salt

Preheat oven 350. Cook the shallots in 2 T of olive oil. I used a cast iron pan so I could cook and bake in one. Add the mushrooms and cook until tender. Prepare the custard by putting everything into a food processor. Add the garlic and herbs to the shallots and mushrooms and saute. Add the spinach by handfuls, waiting for it to wilt before adding the next handful.
Turn off the heat and move the veggies to one side of the pan. Add 1 T olive oil and the bread. Mix it up and distribute with the veggies. Pour the custard over everything and smush it all together. Make sure everything is coated without "outright" mixing it all together.
Bake for 55-60 minutes. When finished, should be firm and lightly browned. Cool 10 minutes and eat!