rhubarb cobbler

INGREDIENTS

• 1 2/3 cups all-purpose flour
• 3 1/2 tablespoons sugar
• 1 tablespoon plus 1/2 teaspoon baking powder
• 2 hard-boiled egg yolks
• 1/8 teaspoon salt
• 6 tablespoons cold unsalted butter, cut into 1/2-inch cubes
• 2/3 cup plus 1 tablespoon heavy cream
• 2 pounds rhubarb, trimmed and cut into 1/2-inch pieces (about 6 cups)
• 1/2 cup sugar
• 1-inch piece of vanilla bean, split lengthwise, pulp scraped
• 2 tablespoons cornstarch
• 1 tablespoon turbinado sugar