½ cup wheat berries, preferably soft white wheat berries
¼ cup hull-less barley
2 tablespoons unsalted butter, plus more for greasing the baking dish
1 medium yellow onion, chopped
2 tablespoons whole wheat flour or whole wheat pastry flour
2 cups milk (whole, 2%, 1%, or fat-free)
3 ounces shredded Cheddar, divided
1½ ounces finely grated Parmigiano-Reggiano, divided
2 teaspoons minced fresh tarragon leaves or 1 teaspoon dried tarragon
1 teaspoon Dijon mustard
½ teaspoon ground black pepper
1. Soak the wheat berries and barley together in a big bowl of cool water for at least 8 and up to 16 hours. Drain the grains in a fine-mesh sieve or small-holed colander set in the sink. Pour the grains into a large saucepan, fill it about three-quarters of the way with water, and bring to a boil over high heat. Reduce the heat to low and simmer until tender but with a little chew in the bite, about 55 minutes. Drain again in that sieve or colander.
2. Position the rack in the center of the oven and preheat to 350°F. Lightly butter a 9-inch square baking dish.
3. Melt 2 tablespoons butter in a large saucepan over medium heat. Add the onion; soften, stirring often, for about 5 minutes.
4. Whisk in the flour until it coats the onion pieces; cook for 30 seconds. Then whisk in the milk in a thin stream. Once all the milk is in the pan, keep cooking, whisking almost constantly, until the mixture bubbles and thickens, about 3 minutes.
5. Whisk in 2½ ounces Cheddar, 1 ounce Parmigiano-Reggiano, the tarragon, Dijon mustard, and pepper until the cheese melts. Then whisk in the drained grains. Pour this mixture into the prepared pan. Top with the remaining Cheddar and Parmigiano-Reggiano, sprinkling both evenly over the casserole.
6. Bake until bubbling and irresistible, about 30 minutes. Cool on a wire rack for 10 minutes before serving.
SERVES 6
Active time: 20 minutes
Total time: 2 hours, plus soaking the grains for at least 8 hours
Make ahead: Cover the casserole and squirrel it in the fridge for up to 4 days.
TESTERS’ NOTES