Puff pastry forms the base for an easy-to-prepare topping of prunes stewed in red wine. Serve with creme fraiche or whipped cream.
Preheat oven to 375 degrees. In a medium saucepan, bring wine, orange juice, 1/2 cup sugar, and cinnamon to a boil over high heat. Remove from heat; add prunes, and let steep 10 minutes. Use a slotted spoon to transfer prunes to a bowl. Return liquid to a boil; cook until slightly reduced and thickened, 10 to 12 minutes. Remove from heat.
Meanwhile, roll out puff pastry into a 12-by-18-inch rectangle. In a small bowl, combine remaining 2 tablespoons sugar and orange zest; sprinkle evenly over pastry. Arrange prunes in rows over pastry, leaving a 1-inch border on all sides. In a small bowl, whisk together egg and cream; brush mixture on edges of pastry.
Bake until crust is golden, about 20 minutes, rotating pan and brushing tart with reserved cooking liquid halfway through. Remove from oven; let cool slightly. Serve warm.