Lightly grease a 23 x 33 cm baking pan and line with parchment paper. Preheat oven to 175°C.
Combine the flour, icing sugar, and butter in a bowl. Rub the butter through the mixture by hand until the texture resembles coarse crumbs, or pulse in a food processor until crumbly.
Press the crumb mixture evenly into the base of the prepared pan. Bake for 20 minutes, or until edges just begin to brown. Remove from oven.
Spread the cherry mixture evenly over the pre-baked base. Return pan to oven and bake for 25–30 minutes, until the topping is set and lightly golden.
Allow to cool completely in the pan. Lift out with parchment, then cut into bars or squares for serving.