Preheat oven to 400 degrees F.
In a small bowl, mix sugar and cinnamon together. Lay puff pastry sheet on a work surface brush with melted butter and sprinkle with half the cinnamon sugar. Cut into 6 even pieces. Fan the pear slices over the puff pastry, using 1/2 a pear for each puff pastry square. Sprinkle tops of pear tarts with remaining cinnamon sugar mixture. Bake until pastry is golden and cooked through, about 20 to 25 minutes.
Remove from tart from oven, sprinkle with cheese and bake until cheese melts, 5 minutes more.