It's like waking up to a warm blueberry muffin straight from the oven, only better. If you love Crumbl's Blueberry Muffin cookies, you're going to love this copycat blueberry muffin Crumble cookie ...
Place all crumble ingredients ... sugar and corn starch. Pour blueberry mixture onto the bottom layer. Sprinkle the remaining oat/walnut mixture onto the top of the blueberries.