I've never tried making this gluten-free. A one-to-one GF flour will probably work well.
750 ml chopped dates 60 ml white sugar 300 ml water Cook the above in a small pot, stirring constantly until it begins to thicken (10 or 15 minutes). Allow to cool. 440 ml flour 2.5 ml baking soda 5 ml salt (I usually just throw in a pinch) 180 ml butter 250 ml brown sugar (packed) 375 ml GF quick oats Cut the flour and sugar into the butter. Add the baking soda, salt and (GF) oats. You should have a crumbly mixture. Spread half of this mixture on the bottom of a greased baking dish (24x34 cm). Press it down firmly. Spread the date mixture evenly on top. Sprinkle the remaining crumble mixture on top. Bake for 25 - 30 minutes at 175 °C. Enjoy!