Tarte aux pommes de grand-mère - Published

http://www.cuisineaz.com/recettes/tarte-aux-pommes-de-ma-grand-mere-11868.aspx
I think I'm getting the hang of converting measurements from Metric to Imperial.
I want to try increasing the baking powder, and I'm curious about using yeast instead! My first attempt was a big hit with Ben, Nikita and Isabelle, but I thought it was too dense - they liked that it was like a custard. But it isn't a custard! :o)
I actually don't know what it is. It isn't a cake, and it isn't a pie...
Oh, and I used Gala apples which cooked just fine. I wonder what difference the other apples would make?
Feb 6 2015: it worked! I added the extra tsp of baking powder, and it made this beautiful cake. The topping evened out the, well, top, so that it had a glossy, golden, flat surface. It doesn't really matter how you arrange the apple, because it gets engulfed by the cake. Now, to reproduce the effect!
Sept 19 2015: I've made this a few times now with the leftover pear mush when using a centrifugal juicer to juice pears. It's delicious, with a little whiskey mixed in.
Nov ? 2015: Now I've made this a few times using apple butter Ben made from the leavings from making apple cider - gave it to one of my neighbours as a thank-you and moving-away gift... I hope it was good!!! For that one, I mixed in some diced apple with the apple butter for a bit of texture.

Part 1: The Batter

Butter to grease the baking dish
3 apples for pies (Gala, Northern Spy, Golden Delicious, Rhode Island Greening, Pippin, Granny Smith, Pink Lady, Gravenstein, Boskoop)
2 eggs
1/3 cup milk

1/4 cup grape seed oil

1 tsp. vanilla extract
3 oz flour (about 3/4 cup, sifted)
4.5 oz granulated sugar (about 1/2 cup)
2 tsps. baking powder 

Part 2: The Topping

3 oz of butter (about 1/3 cup)

1/4 cup icing sugar

1 egg

1. Preheat the oven to 350F.
2. Peel and slice the apple and arrange evenly a lightly buttered spring form pan.
3. Work the batter as little as possible.
4. Thoroughly beat the egg separately, and add the milk, oil and vanilla. Set aside.
5. In another bowl, mix together the flour, sugar and baking powder. Create a well in the centre and add the beaten egg, milk, oil and vanilla, folding gently until the batter is uniform.
6. Pour the batter over the apples, and put in the oven for 15 minutes.
7. While this is baking melt the butter and whisk in the sugar, then set aside to allow it to cool.
8. Just before the timer rings, add the egg and whisk until it all uniform.
9. Pour the butter, sugar and egg mixture on top of the cake and bake for an additional 15-20 minutes, or until the top is uniformly golden (you may have to turn the dish after about 10-15 minutes for even browning).
10. Allow to cool and serve while still warm or at room temperature.