Pear Upside-Down Graham Cake
1 cup all-purpose flour 1 cup whole milk 1 teaspoon baking soda 1 teaspoon ground ginger 1 teaspoon kosher salt 1 teaspoon vanilla extract 1 ½ cups graham flour 1 ½ teaspoons baking powder 2 tablespoons honey 3 large eggs 3 pears - peeled, cored, and sliced 3 ½ tablespoons unsalted butter, cut into pie… ¼ cup dark brown sugar ¼ cup grapeseed oil ½ cup packed dark brown sugar ½ cup unsalted butter, at room temperature ½ teaspoon ground cinnamon