Lemon Blueberry Crunch Muffins via Tasty Kitchen. These were fan-freaking-tastic. And easy to make. A few notes: I didn't have cake flour so I subbed all purpose (3/4C APF + 2 T cornstarch for every 1 C cake flour). Also, I used 1 pint fresh blueberries. I'd cut the amount of butter/lemon juice used for the topping in half, because I had TONS left. I'd use more lemon zest next time too.