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 14x10-inch rectangle.
Fold 1/2 inch of pastry edges in toward center on all sides, forming
13x9-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 crème fraîche, sea salt, 1/4 teaspoon black
pepper, and nutmeg in small bowl. Using offset spatula, spread
crème fraîche over crust to folded edge. Arrange onions
atop crème fraîche. Sprinkle with bacon. Bake tart until
crust is light golden brown and topping is bubbling, 20 to 25 minutes.
Sprinkle with thyme and serve.