Drain the cherries over a bowl. Measure out one cup (250 ml) of the syrup. From that one cup of syrup, measure out 3 tablespoons and place in a small bowl with the cornstarch. Stir well to dissolve the cornstarch.

Place the drained cherries and remaining one cup of syrup (minus the 3 tablespoon syrup-cornstarch mixture) in a small pot. Heat over medium heat until gently simmering. Break apart some of the cherries with your spoon. Give the syrup-cornstarch mixture another stir and add it to the pot. Stir continuously until the filling thickens - just one or two minutes.

Remove from the heat and let cool. You can transfer it to a bowl and place it in the fridge to cool more quickly.

In a medium-large bowl combine all the remaining ingredients except the vegan butter. Stir to mix well.

Cut the butter into small cubes and add it to the crumble mix. There are several different ways you can cut in the butter: with a pastry cutter, smash it with a fork, cut it in with two knives, or use your hands. I find using my fingers to be the easiest. Just press and crumble to butter and flour-oat mixture together until it has a sandy texture with some pea-sized butter chunks (see photo for reference).

Preheat the oven to 350 F / 175 C and line an 8 x 8-inch (20 cm) square or 9-inch (23 cm) round pan with parchment paper.

Add ¾ of the oat-flour mixture to the prepared pan and press it down with your hands. Pour over the cooled cherry filling and spread it evenly. Sprinkle over the remaining ¼ oat-flour topping and lightly press it down.

Bake for 30 - 35 minutes or until the top is golden brown and the filling is bubbling around the edges.

Let cool completely before slicing.