Caramelized Pear Upside Down Cake

PREHEAT the oven to 350F. Melt the butter in a heavy-bottomed 10” cast iron skillet over medium-high heat. Swirl it around the pan several times to ensure it coats the inner sides of the pan as well as the bottom (this will prevent the cake from sticking while it bakes)
STIR, once melted,  in the sugar, allspice, nutmeg and 1 teaspoon of cinnamon.
ADD the sliced pears to the pan as soon as the sugar has dissolved. Gently stir to coat the pears with the butter-sugar-spice mixture, but make sure to keep the pear slices intact. Once the pears are cooked down a bit (softened), slightly browned and well-covered with a thick sticky coating of the cooked sugar/butter mixture, remove the pan from the heat. Spread the pear slices in an even later across the bottom of the pan and set aside.
WHISK together the eggs, oil, water and vanilla in a large mixing bowl. Add the cake mix and remaining 2 tsp cinnamon and stir vigorously until well combined and no clumps remain.
POUR the cake batter over the pears and spread into an even layer.
BAKE in oven for 18-22 minutes, or until a tester comes out clean.
ALLOW to cool for 3-5 minutes in the pan before turning out onto a rack to cool completely.