Prep your pan: Heat the oven to 375°F (190°C). Line a 12-cup muffin tin with paper liners or grease well.
Mix dry ingredients: In a large bowl, whisk the flour, baking powder, baking soda, salt, cinnamon, and lemon zest.
Whisk wet ingredients: In a separate bowl or large measuring cup, whisk the honey, Greek yogurt, milk, oil, egg, and vanilla until smooth.
Combine gently: Make a well in the dry ingredients.
Pour in the wet mixture and use a spatula to fold just until no dry streaks remain. The batter should be thick and slightly lumpy. Do not overmix.
Fold in blueberries: Toss blueberries with 1 teaspoon flour if you want to reduce sinking, then gently fold them into the batter.
Fill the cups: Divide batter evenly among the muffin cups, filling each about 3/4 full.
Sprinkle tops with coarse sugar if using.
Bake: Bake for 16–20 minutes, or until the tops are set and a toothpick comes out with a few moist crumbs. If using frozen berries, add 1–2 extra minutes.
Cool: Let muffins rest in the pan for 5 minutes, then transfer to a wire rack to cool. This helps them set and keeps the bottoms from getting soggy.
Serve: Enjoy slightly warm or at room temperature.
Great with a smear of nut butter for extra protein.