Place the sugar and butter in a 9â oven pie plate or frying pan that can be placed in the oven. Cook the sugar and butter on high heat until it becomes a deep golden brown caramel. Do not stir, as it will form crystals. If crystals do form, wipe the sides of the pan with a brush dipped in water. Add the vanilla and lemon zest and blend. Add the apples, which have been peeled, cut in half, and the seeds removed.
Toss the apples with the cinnamon and place the apples next to each other in a circle outside down. They should overlap in the caramel mixture. Allow them to cook for about 10-15 minutes scooping the caramel over the top of the apples with a spoon. Caramel is extremely hot and dangerous. Extreme care should be taken.
Place the pastry over the top of the pan and carefully tuck the edge into the pan. Place the tart into the middle rack of the oven and bake according to the directions on the pastry package. If using a home made crust cook about the same time or until it turns brown. It is usually about 25 minutes at 400Âº F if using a packaged puff pastry.