In a small saucepan, combine porcini and 1¼ cups water; bring to a boil over medium-high heat. Reduce heat, and simmer until very tender, about 15 minutes.
Melt butter in a large Dutch oven over medium heat. Add gourmet mushrooms, onion, and garlic; cook, stirring occasionally, until onion is tender, about 8 minutes. Add barley and cook, stirring constantly, for 2 minutes. Gradually add broth, 1 cup at a time, stirring constantly and letting liquid be absorbed between each addition. Stir in thyme. Gradually stir in spinach until wilted. Stir in cheese and sherry. Add rehydrated mushrooms and any cooking liquid; stirring to combine.
Recipe by Victoria at https://victoriamag.com/mushroom-barley-risotto-recipe/