Preheat the oven to 325 F/162 C for glass or 350 F/ 176 C for metal.
*** Make the Upside-Down ***
Melt the butter in a saute pan and add the apples. Cook them until they have softened a bit, but not all the way. Carefully remove them from the pan and set them aside.
Put the brown sugar in the bottom of a pie pan or tart pan. Flatten it out so it is well spread.
Pour the butter that was in the pan on the brown sugar, trying to get as much covered as possible.
Arrange the apples on top of the brown sugar and melted butter. Set aside.
*** Make the Batter ***
Sift together flour, baking soda, salt, cinnamon, and mace. Set aside.
Beat together eggs and sugar until the egg mixture is light and smooth. Add the vanilla extract and beat.
Add the oil and beat again.
Slowly add the flour mixture, beating and scraping the sides of the bowl.
Add the apple slices by hand and mix together.
Set aside.
*** Make the Crumb ***
Add the butter, brown sugar, and cinnamon to a small food processor. Process it just until it comes together into a nice crumble. Set aside
*** Assembly ***
Pour the batter over the upside-down and use an offset spatula to flatten it out and make sure it''s all over.
Put the crumb mixture on top of the batter.
Bake for 40 minutes or until a toothpick comes out clean.
Remove it from the oven and let it rest for about 10 minutes.
Get a plate that is larger than your pan and put in upside-down on the top of the pan. Carefully invert the two and remove the pan leaving the upside-down cake.
Notes
You could also do this with a Bundt pan. You would do it in exactly the same order.
This would be excellent with a small scoop of vanilla ice cream when served.
Scan for full nutrition info and step-by-step photos.