First, roast your hazelnuts. Preheat oven to 275° Fahrenheit. Spread whole, unsalted hazelnuts on a cookie sheet and pop in the oven for 15-20 minutes until the outer skin peels away a bit. Remove and pour into a kitchen towel. Let cool a few minutes, then vigorously rub towel so that some of the hazelnut skins are removed. Once the nuts are cool, blitz up in a food processor or nutribullet until you have roasted hazelnut flour. Now make the maple/caramel sauce for the cake:

Preheat the oven to 350° Fahrenheit. Grease a pie plate or 9-inch round cake pan and set aside. In a small sauce pan, heat the maple butter or maple syrup, brown sugar, butter, and salt over medium heat until the sugar is dissolved and the butter is completely melted. Continue to boil for two full minutes (sauce will be thick and caramel-like) then remove from heat and let cool for a few minutes before pouring the sauce into the greased pan. Peel, core, and thinly slice your pears, then arrange in concentric circles on top of the sauce in the greased pan, then set aside while you mix the cake batter.

In a large bowl, beat the butter and white sugar with an electric mixer until lighter and fluffy. Add the eggs, vanilla, spices, and salt and beat until combined. Then, using a spatula, fold in the flour, hazelnut flour, and baking powder. Fold in the milk until combined and smooth, then pour batter over the sauce and pears in the pan, carefully spreading the top so as to not move the pears. Bake at 350 for 40 minutes, then reduce temperature to 325° Fahrenheit and continue to bake for 10-15 minutes until top is browned and a knife when inserted into the center of the cake comes out clean (do not under bake or the center of the cake will be gooey because of the excess liquid from the pears).

Let it cool for 5-10 minutes before putting a plate over the cake and flipping the entire pan onto to the plate. Let it continue to cool for 10-20 minutes before slicing and serving. Great on its own or with a scoop of vanilla ice cream or creme fraiche!