Cut the apples into 8 wedges each;
Place wedges in a bowl with water and lemon juice to keep them from turning brown;
In a deep skillet (10 incwith an ovenproof handle, over low heat, place the butter and sugar until they are melted together;
Drain and arrange the apple wedges neatly in the skillet (remember the tart will be flipped and the apples will be showing), making sure there are no gaps;
Cook the apples over low heat for 30 minutes or until apples are tender, the excess liquid has evaporated and the caramel is golden brown. Remove from heat;
While the apples are cooking, thaw pastry sheet at room temperature;
Preheat oven to 375ยบ;
On a lightly floured surface open the pastry and cut a circle slightly larger than the skillet. Prick the pastry with a fork;
Carefully place the pastry over the skillet, press down on the edges to enclose it completely and fold the excess back on itself. This will make a neat finish;
Bake for 30 minutes, until pastry is golden. Remove from oven and let it rest for about 5 minutes before flipping on the serving plate;
When you flip, place the plate over the skillet and turn swiftly. If there are any wedges stuck on the skillet, just put it back on the gap it left in the tart;
Serve hot with a scoop of vanilla ice cream or a dollop of whipped cream.