1Preheat the oven to 350°F and spray an 8 or 9-inch round cake pan or deep pie plate with nonstick spray.
2To make the topping, melt the butter, honey and brown sugar in a small saucepan over medium heat or microwave it until it’s smooth. (Or combine them in the bottom of the pan, put it in the oven until it melts, then take it out and stir it with a fork until it’s smooth.) Pour the mixture over the bottom of the pan and arrange the pear slices on top, placing them tightly together – they shrink a bit as they cook, so you can even get away with overlapping them.
3To make the gingerbread batter, beat the butter and brown sugar in a medium bowl until well blended. Add the egg, molasses, ginger and vanilla and beat until thoroughly combined. It will look separated - that’s OK.
4In a small bowl, stir together the flour, baking soda, cinnamon, allspice and salt. Add half of the dry ingredients to the molasses mixture and stir by hand or on the lowest speed of an electric mixer just until the batter is combined. Add the buttermilk, and then the remaining dry ingredients in the same manner. Pour the batter over the sliced pears.
5Bake the cake for about 40 minutes, until the top is springy to the touch. Let it stand for 5 minutes, then run a knife around the edge of the cake and invert it onto a plate while it’s still warm. (If it cools too much and sticks to the pan, warm it in the oven again before you try to invert it.) Don’t worry if any pear slices stick to the bottom of the pan – simply peel them out and place them back on top of the cake where they belong.
6Serve with whipped cream. Serves 8.