Preheat the oven to 350°F. Set six 1-cup non-stick ramekins on a baking sheet; place the baking sheet close to the stove.
To make the caramel pears, peel and core the pears and cut each one into 8 wedges. Combine the sugar and water in a heavybottomed saucepan over medium heat, stirring until the sugar dissolves. Increase the heat to high and bring to a boil; cook, without stirring, until the mixture turns a rich caramel colour, 6 to 8 minutes. Very carefully divide the hot caramel equally among the ramekins. Quickly arrange three or four pear slices over the caramel in each ramekin; set aside.
To make the spice cakes, stir together the flour, baking powder and spices in a small bowl.
In a large bowl, beat the butter and sugar together with an electric hand mixer until wellcombined. Stir in the vanilla and add the eggs one at a time, beating for 1 minute after each addition until light and fluffy. In two or three additions, add the flour mixture to the butter mixture, alternating with the milk, beating well after each addition. Carefully spoon the batter evenly over the caramel pears in each ramekin. Bake the cakes for about 35 minutes, until the tops are light golden and set.
Remove the baking sheet from the oven and, working quickly, run a sharp knife around the edges of each cake to loosen; gently turn each cake out onto a small dessert plate. Serve immediately with crème fraîche or whipped cream on the side.