Preheat the oven to 375 degrees F. Line a square baking dish with parchment paper so that it hangs over both sides.
Put the gluten free oats, gluten free flour blend, vegan butter spread, and brown sugar in a large bowl. Use a pastry blender or two knives to mix the buttery spread into the dry ingredients. The mixture should resemble large crumbs, and there should be some balls of brown sugar and butter.
Place half of the oatmeal mixture in the bottom of a 8x8 square baking dish. Use your hands to pat it down.
Bake the bottom crust for 15 minutes. Remove from oven.
Put the raspberries in the pan, and spread evenly over the crust. Top with the remaining oatmeal crumble mixture.
Bake at 375 degrees F for about 25 minutes, until the raspberries are bubbling and the topping is golden brown.
Let cool before slicing into bars.
Notes
Store leftover raspberry bars at room temperature for 3 days. If you want to keep them longer than that, store in the refrigerator.