Preheat your oven to 350 degrees. Liberally grease an 8-inch round baking pan with 2 tablespoons butter, leaving most at the bottom.
In a small bowl, whisk together the brown sugar, cinnamon, nutmeg and sprinkle evenly over the bottom of the pan. Lay the sliced peaches in concentric circles on top of the brown sugar.
In a large bowl, beat the remaining 6 tablespoons of butter and sugar until light and fluffy.
Add the eggs, egg yolk, vanilla extract, and mix until thoroughly combined.
In a small bowl, whisk together the flour, almond flour, baking powder, and baking soda.
Fold in half of the flour mixture into the butter followed by the almond milk and finally the remaining dry ingredients.
Carefully pour the batter over the peaches and level out with a spatula.
Bake for 35-40 minutes or until a toothpick comes out clean. Allow to rest on a wire rack for 10-15 minutes and then invert onto your serving dish. When cool, sprinkle the top with slivered almonds and sifted confectioner’s sugar.