Step 1
Preheat the oven to 350 degrees F (175 degrees C). Grease a 9-inch square deep baking dish.
Step 2
Combine raisins and Marsala wine in a bowl; set aside to soak.
Step 3
Sift cassava flour twice into a large mixing bowl. Mix in superfine sugar baking powder cinnamon and nutmeg. Add almond meal and buckwheat flour and sift all the dry ingredients together.
Step 4
Combine eggs butter milk oil and vanilla extract in a bowl. Beat on low for with a hand mixer for 1 minute until well combined. Beat on high until fluffy for a full 2 minutes. (This is a crucial step to ensure a fluffy cake.) Mix in grated apple. Stir in raisins and wine until combined.
Step 5
Carefully fold egg mixture into flour mixture with a rubber scraper folding with light yet deep strokes from the bottom to the top until batter is just combined and still a bit lumpy with no visible pockets of flour being careful not to overmix. Pour batter into the prepared baking dish.
Step 6
Arrange apple slices to completely cover the batter making sure they do not overlap too much; you may not need all of the slices. Sprinkle with raw cane sugar and pine nuts.
Step 7
Bake in preheated oven until a toothpick inserted into the center comes out clean about 30 minutes. Switch to the broiler function and cook until the top is slightly browned about 2 minutes.
Step 8
Remove from the oven and allow to cool slightly before cutting and serving.