Heat oven to 375°F. Line a muffin tin with 10-12 paper liners or spray each cup with a nonstick spray. OR even better, use silicone baking cups. (The original recipe says it will make 9 muffins, but it made 12 muffins for me. I was generous with the blueberries...)
Pour melted butter in the bottom of a large bowl and whisk in sugar, zest, yogurt and egg until smooth. Whisk in baking powder, baking soda and salt until fully combined, then lightly fold in flour and berries. Batter will be very thick, like a cookie dough. Divide between prepared muffin cups and sprinkle each with about 1 teaspoon turbinado sugar (there's not an excessive amount of sugar in the batter, so don't freak out. It will provide a delicious crunchy top).
Bake for 25 to 30 minutes, until tops are golden and a tester inserted into the center of muffins comes out clean. Let cool in pan for 10 minutes, then cool completely on a cooling rack (as if... we definitely eat them warm).
Source: Smitten Kitchen