Preheat the oven to 350° F. Lightly grease a 9-inch round cake pan and set on top of a baking sheet. Set aside. *See Note 2 below for other pan options.
In a large saucepan, bring the maple syrup to a boil over high heat, then reduce heat to low and simmer until very thick and reduced to 1/2 cup, about 20 minutes. *Use a large pot and watch as it approaches boil, as it will bubble up considerably! While the syrup is simmering, you can peel and cut your apples. Pour the thickened syrup into the prepared pan. Arrange the apples in the pan in 2 concentric circles, overlapping them slightly. *See Step-by-Step photos above this recipe card for a visual of this.
In a bowl, whisk together the flour, baking powder, baking soda and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar at medium speed until fluffy, about 3 minutes. Beat in the eggs one at a time. Beat in the vanilla. Add the dry ingredients alternately with the milk until the batter is smooth. Scrape down the side of the bowl.
Pour the batter over the apples and spread it into an even layer. Place cake pan on top of a baking sheet, to catch any bubble-overs.
Bake the cake for about 30-40 minutes or until a tester inserted in the centre comes out clean. Let the cake cool in the pan, on a cooling rack for 45 minutes. *Baking time will vary by oven and colour of pan. Mine took about 34 minutes. Start checking it about 30 minutes and test when it looks set and golden in colour.
Once cake has cooled in pan for 45 minutes, place a plate on top of the cake and invert the cake onto the plate. Tap lightly to release the cake, if necessary. Remove the pan. Let the cake cool slightly or completely before serving. Garnish with a dusting of icing/confectioners' sugar, if desired. Serve with vanilla ice cream and extra maple syrup, if you like.
1.Make your own buttermilk, if you like! Mix 3/4 cup regular milk with 2 tsp lemon juice or white vinegar. Let stand 10 minutes and use.2. If you don't have a 9-inch round baking pan, you can use a 8-inch round baking pan, but you will need to hold back some of the batter, as it probably won't all fit. Fill pan to the level shown in the step-by-step photos above the Recipe card.Be sure to read the Baking Tips above the recipe card, for more tips on making this recipe.