In New Orleans, bread pudding is usually a dessert. But not this one. Out come the sweet ingredients, replaced by mushrooms, onions, and cheese. It’s my wife Mary Ann’s idea, and we often use it as side dish, especially for Thanksgiving. The dish is at its best with meaty, wild-tasting mushrooms: portobellos, criminis, shiitakes, chanterelles, porcinis, etc. The best cheeses are the ones that melt well and have an interesting tang: Gruyère, fontina, Swiss, provolone, mozzar