Preheat oven to 180 C.
Prepare the filling by mixing all ingredients together. Set aside.
Prepare the topping by mixing all ingredients together with a fork until they form small clumps.
For the base, combine the cold butter, flour and sugar in a bowl. With a fork or pastry blender, mix everything together all while breaking the cubes of butter into small pea sized pieces. Add the water 1 tablespoon at a time and stir with a spoon until the mixture comes together into a dough. Don’t add more water than is necessary.
Line a 6 inch square baking tin with parchment paper. Press the base dough evenly on the bottom of the pan. Spread the filling over the base and sprinkle the crumble topping over it.
Place the baking pan on the medium rack and bake for 45 minutes.
After 45 minutes, place the baking pan on the top rack and bake for 15 minutes so that the crumb topping gets nicely browned.
Allow to cool completely.
For the glaze, mix the powdered sugar and water until a thick paste forms. Use a fork or spoon to drizzle the glaze over the cooled bars. Cut into squares and serve.
