Preheat your oven to Gas 5, 375°F, 190°C.
Prepare the plums by chopping at least cm in thickness.
1000 grams Plums
In a mixing bowl, combine the chopped plums, plum jam, granulated sugar, vanilla extract, and a pinch of salt. Toss to coat the plums evenly. Set aside.
2 tbsp Golden Caster Sugar, 1 tsp Vanilla Extract, ½ tsp Himalayan Salt, 340 grams Plum Jam
In another bowl, combine the flour, baking powder, rolled oats, sugar, spices, and salt. Add the cold cubed butter and use your fingertips to rub the butter into the dry ingredients until the mixture resembles coarse crumbs.
150 grams All-Purpose Flour, 100 grams Coconut Sugar, 100 grams Rolled Oats, 100 grams Butter, 1 tsp Baking Powder, 1 tsp Ground Ceylon Cinnamon, ½ tsp Ground Allspice
Using your fingers, a food processor, or a pastry cutter, work the butter into the dry ingredients until the mixture resembles coarse crumbs.
Divide the crumble mixture into about 1/2 and 1/2.
Put one portion of the 1/2 into the greased baking dish and flatten with a clean spoon, flat-based cup, or glass.
Add the plum mixture mixture to the baking dish.
Sprinkle the other 1/2 portion of the crumble mixture evenly over the plum filling in the baking dish.
If you're using slivered blanched almonds, now's the time to sprinkle some over the top of the crumble.
60 grams Slivered Blanched Almonds
Place the baking dish on a baking sheet to catch any potential drips, and bake in the preheated oven for about 35-45 minutes, or until the plums are tender and bubbling, and the crumble topping is golden brown.
Remove from the oven and let it cool slightly before serving.
Enjoy your homemade crumble!