Honey Roasted Plums

1/2 cup (packed) dark brown sugar
1/4 cup honey
4 tablespoons (1/2 stick) unsalted butter
6 large assorted ripe but firm plums (about 2 pounds), halved, pitted
Crème Fraiche

Preheat oven to 475°F. Stir first 3 ingredients in large ovenproof nonstick skillet over high heat until butter melts.
Cook 2 minutes, stirring constantly (mixture will bubble vigorously).
Add plum halves, cut side down. Cook plums without stirring for 2 minutes.
Turn plums over and transfer skillet to oven.
Roast until caramel is deep brown, checking frequently to prevent burning, about 4 minutes.
Divide plum halves among 6 plates.
Spoon sauce from skillet over plums. Drizzle plums with crème fraiche,
Sprinkle with fresh thyme (optional) and serve