Vegan Plum Crumble Cake

Name: Vegan Plum Crumble Cake
Prep time: 25 min
Cook time: 45 min
Total time: 1 h 10 min
Cuisine: British
Ingredients: 150 g plain or all-purpose flour (BL55); 30 g cornflour (US -cornstarch) (cornstarch); 100 g soft brown sugar; 1 tsp baking powder; 1 tsp vanilla extract, sugar or 1/2 tsp of vanilla paste; 75 ml neutral-tasting oil (coconut, vegetable or sunflower oil); 150 ml non-dairy milk (almond, oat, rice or soy milk) (room temperature); 1 pinch fine sea salt; 500 g fresh plums; 30 g soft brown sugar (2 tbsp); 1/2 tsp ground cinnamon; 100 g plain or all-purpose flour; 50 tsp soft brown sugar; 50 ml coconut oil