1. Preheat oven to 350ºF and lightly grease a 9-inch springform pan. Set aside.
2. Mix together flour(s), baking powder, and salt in a large mixing bowl. Add melted butter, sweetener, milk, and vanilla. Beat 2-3 minutes or until smooth, scraping down the sides as needed.
3. Scoop batter into the springform pan and smooth evenly throughout the pan.
4. Core apples and cut in half. Slice each half thinly and arrange slices onto the batter in the pan.
5. Place springform pan onto a baking sheet and place on the middle rack in the preheated oven.
6. Bake for 40–50 minutes or just until cake is lightly brown and a toothpick inserted near the center comes out with only a few moist crumbs.
7. Let cool slightly and run a knife around the edges to loosen the cake from the sides of the pan. Remove the outside of the springform pan and carefully separate the bottom of the cake from the metal bottom with an offset spatula. Carefully transfer to the serving plate. Yields 8-10 servings.

To make hibiscus glaze: (adds color, but can also be made without it)

1. Boil water and steep tea for several minutes, until desired color is reached. Should be deep red. Strain loose tea/ bags, pressing out as much water as possible.
2. Place tea in a shallow dish and add peeled apple slices. Let soak for 10–15 minutes, or until apples are dyed pink.
3. Lightly shake off apples and place on top of cake batter in the pan. Sprinkle with turbinado sugar, optional. Bake cake for 40–50 minutes or until center is set.
4. Meanwhile, boil remaining tea until liquid is reduced and more concentrated (I added a little more loose tea to depend the color) Add sweetener and continue to boil for a few minutes, until thickened. Remove syrup from heat and cool. Brush syrup over cooled cake and serve.