Sprinkle the sugar and most of the cinnamon over the cut sides of the pears, and leave to stand for 10 minutes to allow the sugar to dissolve.
Heat a griddle pan over a medium heat and place the pears cut-side down in the pan. Griddle for 5 minutes, until heated through and caramelised.
Transfer to a plate and top with a spoonful of yogurt. Dust with the remaining cinnamon.