Sherry-Scented Mushroom Duxelles

Working in about 4 batches, pulse mushrooms in a food processor until very finely chopped, about 8 pulses per batch. Transfer chopped mushrooms to a bowl; set aside.

Melt butter in a large skillet over medium. Add shallots and a pinch of salt, and cook, stirring often, until shallots are softened, about 3 minutes. Add finely chopped mushrooms, pepper, and remaining 1/2 teaspoon salt. Increase heat to medium-high, and cook, stirring occasionally, until mushrooms start to release their liquid, about 6 minutes. Reduce heat to low; cook, stirring occasionally, until liquid has evaporated and mushrooms look dry, about 20 minutes. Stir in sherry, thyme, and nutmeg, and cook, stirring occasionally, until sherry has evaporated, about 2 minutes. Remove pan from heat. Season duxelles with salt and pepper to taste. Let cool slightly, about 10 minutes.