Make the gingerbread
Position a rack in the center of the oven and heat the oven to 350°F. Coat an 8- or 9-inch square cake pan (at least 10 cups in volume) with the butter and lightly dust with the granulated sugar. In a small bowl, stir the oil, molasses, and eggs until combined. In a large bowl, whisk the flour, baking soda, ginger, cinnamon, and salt.
In a small pot, bring the brown sugar and root beer to a boil. Meanwhile, add the molasses mixture to the flour and stir to combine. Add the hot root beer mixture and quickly beat until combined. Pour the batter into the prepared pan and bake until a toothpick inserted in the center of the cake comes out clean, 35 to 45 minutes. Let cool in the pan on a wire rack until warm, about 40 minutes. Invert the pan to remove the cake and turn the cake right side up. (The cake may be prepared up to 4 hours ahead.)
Poach the pears
In a medium saucepan, combine the pears, root beer, and lemon zest. Bring the mixture to a slow simmer over medium-low heat and cook until the pears are tender, 20 to 30 minutes. With a slotted spoon, carefully transfer the pears to a plate. Bring the poaching liquid to a boil and boil until reduced to a syrup, about 15 minutes (watch carefully towards the end because it can burn quickly); you should have about 3/4 cup. (The pears and syrup may be prepared up to 4 hours ahead. If the syrup thickens, reheat before serving.)
In a chilled medium bowl, beat the cream and sugar with a hand mixer until soft peaks form, about 3 minutes. Cut the gingerbread into 8 pieces of whatever size you choose and place one on each of 8 plates. Arrange a pear half against each piece of gingerbread and drizzle each with the syrup. Top with a dollop of whipped cream and serve.
nutrition information (per serving):
39, Fat Calories
340, Saturated Fat
6, Monounsaturated Fat
112, Polyunsaturated Fat
Photo: Christopher Hirsheimer; food styling by Melissa Hamilton