Preheat oven to 350 degrees. Sift together the flour, baking powder, cinnamon, nutmeg, and kosher salt into a bowl. Set aside. Using 1 tablespoon of the butter, grease a 9-inch glass pie dish and arrange applesin a sigle layer, like a fan. Combine 1 cup of the granulated sugar and 1/3 cup of water in a saucepan, cooking over high heat until the mixture turns into a warm amber color. Do not stir. Pour carefully over apples. Using a stand mixer with a paddle attachment, mix the remaining 6 tablespoons of butter on medium speed with 3/4 of the granulated sugar until fluffy. Lower the speed and beat in one egg at a time. Add the ricotta, zest, vanilla, and mix until all is combined. Add the dry ingredients and mix only until combined. Pour the cake batter evenly over the apples and bake for 30 to 40 minutes or until "the toothpick" comes out clean. Cool for 15 minutes, then invert cake onto a serving plate. Serve at room temperature, dusted with the confectioner's sugar.