A simple and delicious wild mushroom gratin. I've used cauliflower mushrooms here because we had found a large, fresh one this year and despite it's delicate appearance, it keeps a nice firm texture once cooked. This would be wonderful with other wild mushrooms too, like chanterelles or a mixture of soft and firm mushrooms like lobster and oyster. I added spinach for the color and vitamins but my husband and daughter both preferred this without spinach so feel free to omit it if you don't love cooked spinach.
Preheat oven to 350'F
Make the bread crumb mixture by pulsing garlic, parsley and salt in a food processor until the garlic is chopped well, then add the bread and pulse until it is an even fine bread crumb mixture.
Heat the oil in a large pan on medium, once heated, add the mushrooms and saute until they are cooked down and liquid is gone, then add stock and simmer until liquid is reduced by half.
Add sour cream, 1/2 cup of the cheese, and spinach if using. Stir gently to incorporate and wilt spinach, then add 1/2 of the bread crumb mixture and stir in. Season to taste with salt and pepper then scrape mixture into an oven safe 9x7 baking dish.
Mix bread crumbs and remaining 1/2 cup of cheese together and sprinkle evenly over mushroom mixture and bake in oven until browned on top, approximately 20 minutes.