An optional garnish of fried sage leaves takes this rustic gratin from simple to spectacular.
Reprinted from Meatless: More Than 200 of the Very Best Vegetarian Recipes. Copyright © 2013 by Martha Stewart Living Omnimedia, Inc. Photos © 2013 by Johnny Miller. Published by Clarkson Potter/Publishers, a division of Random House, Inc.
Martha Stewart Living Omnimedia, Inc.
| 2 tablespoons olive oil | 1 tablespoon chopped fresh sage leaves, plus whole leaves for garnish | |
| 3 tablespoons all-purpose flour | Coarse salt and freshly ground pepper | |
| 1 cup whole milk | 2 pounds sweet potatoes, peeled and sliced 1/4 inch thick | |
| 1 cup water | 1 head cauliflower, trimmed, quartered, and sliced 1/4 inch thick | |
| 1/4 cup plus 1 tablespoon finely grated Parmigiano-Reggiano | Canola oil, for crisping |
Preheat oven to 350°F. Heat olive oil in a pot over medium. Add flour and cook, stirring, 1 minute. Slowly whisk in milk and the water. Cook, whisking, until thickened, about 12 minutes. Remove from heat; stir in 1/4 cup cheese and the chopped sage. Season with salt and pepper.
Pour one-third of sauce in bottom of a 3-quart shallow baking dish. Arrange a third of the sweet potato and cauliflower in an overlapping layer, alternating vegetables. Season with salt and pepper. Repeat twice with remaining sauce and vegetables. Cover with parchment, then foil; bake until tender, about 1 hour.
Raise oven temperature to 425°F. Uncover and sprinkle with remaining cheese. Bake until golden brown, about 20 minutes. Let stand 10 minutes.
Meanwhile, if desired, heat 1 inch canola oil in a small pot over medium- high until shimmering. Cook a few sage leaves at a time until crisp, about 10 seconds. Transfer to a paper towel to drain. Season with salt. Sprinkle leaves onto gratin and serve.