Preheat the oven to 350F degrees. Cut the plums in half and remove the stone. Cut each half into 3 slices and place them in a casserole. Add the rest in a second layer on top. Depending on how ripe/sweet the plums are and how sweet you like desserts you can optinally sprinkle the plums with about 1 Tbsp of maple sugar.
In a medium mixing bowl combine tapioca flour, coconut flour, cinnamon, salt and stir well. Add honey and coconut oil and mix until crumbles form. Make sure you mix and squeeze the dough long enough through your hands to achieve the perfect crumble consistency. It should not look like a bunch of flour. If you cannot achieve this texture add a bit more coconut oil.
Finish up by distributing the crumbles evenly on top of the plums.
Bake for about 35 minutes or until the plums are soft and juicy, and the crumbles are golden brown. Remove and cover with a baking sheet for 5-10 minutes. The steam will make it a lot juicier.Serve warm with compliant ice cream, coocnut cream or coconut yogurt. Enjoy!