Any plums will do in this simple, exquisite cake.
Preheat oven to 350 and butter an 8" cake pan.
Slice 2-3 plums and roughly chop a handful of almonds.
Whisk together:
6 T of melted and cooled butter
2/3 cup maple or brown sugar
2 T maple syrup
1 t vanilla
1 egg
In a separate bowl, mix:
1 cup almond meal
3/4 cup flour
1/4 t salt
1/2 t baking powder
Add the dry ingredients to the wet and fold until just mixed. Pour into your prepared pan and spread gently (the batter will be quite thick).
Arrange the plum slices over the top, scatter the chopped almonds and a pinch of sugar, then bake for 20-25 minutes.