Mushroom and Celery-Root Bread Pudding

Preheat oven to 400 degrees. Combine milk, cream, and celery root in a small saucepan. Bring to a boil, then reduce heat and simmer until celery root is fork-tender, about 10 minutes. Let cool slightly. Transfer mixture to a blender; puree until smooth. Season with salt and pepper.

Meanwhile, lightly toast bread on a rimmed baking sheet, tossing once, until golden and crisp, about 10 minutes.

In a large skillet, melt butter over medium-high heat. Add mushrooms and cook, stirring occasionally, until they have released most of their moisture and become golden, about 9 minutes. Add 2 tablespoons water and bring to a boil, scraping up browned bits with a wooden spoon; cook until water evaporates. Season with salt and pepper. Transfer to a bowl.

Butter a shallow 2-quart baking dish. In a large bowl, whisk together celery-root mixture, eggs, and thyme leaves. Fold in toasted bread and mushrooms. Transfer to prepared dish; sprinkle with cheese. Garnish with thyme sprigs and bake until custard is set and top is lightly browned, 20 to 25 minutes. Let cool slightly before serving.