Line an 8x8 baking dish with a parchment sling and spray with nonstick spray. Set aside. In a large bowl, combine the flour, oats, brown sugar, salt, baking soda, and cinnamon. Mix together until evenly combined. Add pieces of butter and work into the dry ingredients using hands or a pastry cutter. Squeeze butter and dry mixture between fingers until the mixture becomes like went sand with pieces of butter the size of peas and smaller.
Pour two cups of the crumb mixture into the prepared baking dish. Lightly press to form an even crust. Spread raspberry preserves over the crust. Sprinkle with frozen raspberries. Top with remaining crumb mixture. Do not press crumbs, just sprinkle over the top.
Bake in the preheated oven until the top turns slightly browned and puffed in the middle, 30-35 minutes. Remove from oven and cool at least four hours before slicing.