8 tbsp gluten-free quick oats (or use sliced almonds for a grain / oat-free version)
2 tbsp maple syrup
cinnamon for sprinkling (optional)
Pre-heat oven to 350F. Lightly oil a small baking dish (I used a medium-sized ceramic 22 oz / 3 cups oval baking dish, but anything of a similar size will do).
Place all plum base ingredients in the baking dish and toss / stir around to combine (make sure the dish is not filled to the top -- you need a good 1" clearance to the top in there because the mixture will rise and then drop back down as it cooks, so don't over-fill).
Sprinkle evenly with the quick oats. Drizzle the additional maple syrup on top of the oats. Sprinkle with some cinnamon (optional).
Bake in a pre-heated oven for 1 hour. Remove and allow the crumble to cool off a bit (or a lot of you like it cold). Top with an ice cream of your choice (see notes above recipe for ice cream recipe recommendations) and serve. Enjoy!