Position rack in top third of oven and preheat to 375°F. Using lightly floured rolling pin, roll out puff pastry on lightly floured surface to 14×10-inch rectangle. Fold 1/2 inch of pastry edges in toward center on all sides, forming 13 x 9-inch rectangle. Transfer pastry to large rimmed baking sheet. Press firmly on pastry edges with fork to form rim. Chill crust. Cook bacon in small skillet over medium heat until brown and crisp. Transfer to paper towels to drain. Reserve 1 tablespoon bacon drippings from skillet. Whisk honey, wine, and reserved 1 tablespoon bacon drippings in large bowl. Add onions; toss to coat. Coat another large rimmed baking sheet with nonstick spray. Spread onion mixture in even layer on sheet. Roast 30 minutes. Turn onions over, allowing rings to separate. Roast until onions are caramelized, turning often for even browning, 30 to 45 minutes. Remove from oven; cool onions slightly. Increase oven temperature to 400°F. Mix creme fraiche, sea salt, 1/4 teaspoon black pepper, and nutmeg in small bowl. Using offset spatula, spread creme fraiche over crust to folded edge. Arrange onions atop creme fraiche. Sprinkle with bacon. bake tart until crust is light golden brown and topping is bubbling, 20 to 25 minutes. Sprinkle with thyme and serve.