Preheat the oven to 400 degrees Fahrenheit. Spray a 2-quart baking dish with cooking spray.
In a large bowl, combine cherries, lemon juice, arrowroot starch, ¼ cup + 2 tablespoons coconut sugar, and ¼ teaspoon vanilla extract. Transfer mixture to prepared baking dish and bake for 15 minutes on lower rack.
In a medium bowl, combine the almond flour, arrowroot starch, sliced almonds, salt, coconut sugar and cinnamon. Whisk to combine. Add the melted coconut oil and vanilla extract. Stir to combine and moisten ingredients, then use your hands to squeeze crumble ingredients together.
Once the cherries have baked for 15 minutes, remove from oven. Squeeze handfuls of crumble mixture and place atop the cherries in an even layer (being careful because dish is hot). Use oven mitts to place dish back in the oven on the middle rack. Bake for 8-12 minutes until browned, careful not to burn. Allow crumble to cool for 20 minutes before serving.