Ingredients
12 tablespoons chilled (1 1/2 sticks) unsalted butter, cut into small pieces, plus more for ramekins
1 cup plus 1 1/2 tablespoons all-purpose flour
1/2 cup packed dark-brown sugar
1/2 teaspoon ground cinnamon
1/4 teaspoon grated nutmeg
1/4 teaspoon salt
1/2 cup old-fashioned rolled oats
2 pounds (6 large stalks) rhubarb, cut into 1/2-inch pieces (6 cups)
1 teaspoon grated orange zest
Juice of 1 orange
1 vanilla bean, split and scraped
1/2 cup granulated sugar
2 tablespoons cornstarch
Preparation
Preheat oven to 375 degrees. Butter six 8-ounce ramekins (or a 2 1/2-quart shallow casserole), and set aside. Make crumb mixture: In a large bowl, whisk together flour, brown sugar, cinnamon, nutmeg, salt, and oats. Using a pastry cutter or two knives, cut in chilled butter until mixture comes together into clumps, about 4 to 5 minutes; set aside.
In a large bowl, stir to combine rhubarb, zest, orange juice, and vanilla seeds. In a small bowl, combine sugar and cornstarch; sprinkle over rhubarb until just coated. Pour 1 cup rhubarb mixture into each ramekin, and top with 1/2 cup crumb mixture. Bake until the rhubarb is tender when pierced with the tip of a knife, about 30 minutes (or about 40 minutes for the casserole). Transfer from oven to a cooling rack. Let cool slightly, and serve warm.
