Peel, halve, and core pears.

In a 9- to 10-inch heavy skillet heat butter over moderate heat until foam subsides.

Stir in sugar (sugar will not be dissolved).

Arrange pears, cut sides up, in a skillet, with the skinny end of pears pointing into the middle of the pan.

If you have a half of a pear left over, cut a circle out of it and place it in the middle of the skillet domed side down.

The pears will make a sort of flower in the skillet.

Cook without stirring until sugar mixture forms a deep golden caramel.

Cool pears completely in skillet. Sprinkle it with cinnamon and ginger.

Preheat the oven to 425°f and set a rack in the upper third of the oven.

On a lightly floured surface with a floured rolling pin roll out dough into a 12-inch round (about 1/8 inch thick) and arrange over pears.

Tuck edges into the skillet around pears.

Bake tart in the upper third of the oven until the pastry is deep brown, 30 to 35 minutes.

Remove from the oven and let rest 5 minutes, but not longer.

Have ready a rimmed serving plate slightly larger than skillet.

Invert plate over skillet and, wearing oven mitts and keeping plate and skillet firmly pressed together, invert tart onto plate.

Do this over the sink in case some juices spill.

This is a bit scary, but it works!

The trick is to do it in one very fast motion.

Let cool until warm, 10-15 minutes.

Serve tart warm with whipped cream or creme fraiche.