Preheat oven to 200`c. Put a 21cm-diameter frying pan with an ovenproof handle on a hob over a medium heat. Add the sugar and heat to a lovely caramel colour, stirring constantly. Add the butter, ginger and cinnamon and stir to combine. Place the pears in the caramel and spoon over the mixture. Turn the heat down and cook for 5–10 minutes, until the pears are just tender and cooked but retain their shape. Remove from the heat and cool slightly. Arrange the pears prettily in the pan. Roll out the pastry to about 5mm thick and cut a disc slightly bigger than your pan (about 24cm). Place the pastry disc on top of the pears and caramel, then carefully tuck it snugly around the outside of the pears and down into the sides of the pan. Bake for 30–40 minutes, or until the pastry is golden brown and puffed up. Remove from the oven and leave for 10 minutes. Run a knife around the edge, place a large plate over the top and carefully turn the tart onto the plate. Serve sprinkled with a few fresh thyme leaves and a dollop of cream.