Preheat oven to 350 degrees F. Lightly grease a 9-inch round cake pan or 2-inch deep 9-inch pie dish.
In a sauté pan melt 2 Tablespoons butter and add the pears. Sprinkle with cinnamon. Sauté until the pears have softened. Once cool enough to handle place pears in the prepared pan in concentric circles starting in the center and working out to the edge. Pour the Dulce de Leche over the pears.
In the bowl of an electric mixer fitted with a paddle attachment cream together 6 Tablespoons softened butter and the granulated sugar until fluffy. Add the eggs and vanilla and cream until uniform.
In a medium bowl with a whisk combine the flour baking powder, baking soda, and salt. With the mixer on low alternately add the flour mixture and the buttermilk to the butter. Mix until incorporated and smooth, but do not over mix. Spread the cake batter over the pears, making sure it touches the sides of the dish.
Bake for 45-50 minutes until a toothpick or cake tester comes out clean when inserted into the center of the cake. When done, run a knife around the edge of the cake. Allow to sit 5 minutes before turning out onto a serving dish.