Preheat the oven to 350┬║F. Place the butter and sugar in a small pot and cook, stirring constantly, over medium heat until the sugar has melted and caramelized, about 8 minutes. Remove the pot from the burner and add the cream. It will bubble and spit, so be careful. When the sauce has calmed down, return to the flame and add the wine slowly while continually stirring. Add the vanilla scrapings and lemon juice.
Add half the red wine caramel sauce to a 10-inch cast-iron or regular ovenproof skillet. Place the apple halves, cut side up, making sure the apples are snug. Cover the top of the pan completely with the puff pastry by overlapping the two sheets. Snip off the extra dough with scissors to create a circle that just fits inside the pan. Bake for 30 minutes, or until the puff pastry has risen and is golden brown.
Let the tarte rest in the pan for 15 minutes; then place your serving platter on top of the pan, and carefully flip it over. Lift the pan away from the tarte; the beautiful apples will now be on top. Decorate the dessert plates with the remaining sauce, add a slice of the tarte, and garnish with the thyme.
Edited: October 12th, 2009