Heat oven to 375°F and position rack in the middle. Line a 12-cup muffin pan with paper liners or lightly grease cups with oil or butter.

In a medium bowl, whisk together flour, baking powder, baking soda, salt, and sugar. Set aside.

In a blender or food processor, blend cottage cheese, eggs, oil, vanilla, and lemon zest (if using) until completely smooth, about 30–45 seconds. No curds should remain visible.

Pour blended wet mixture into the bowl with dry ingredients. Gently fold with a spatula until just combined—batter will be slightly lumpy. Do not overmix.

In a small bowl, toss blueberries with 1 tablespoon flour until coated. Gently fold blueberries into batter with just 3–4 strokes. Some streaks of flour on berries are fine.

Divide batter evenly among muffin cups, filling each about ¾ full (about ¼ cup batter per muffin).

Bake 18–22 minutes, until tops are lightly golden and spring back when touched, and a toothpick inserted in center comes out clean or with just a few moist crumbs. If using frozen berries, may need extra 2–3 minutes.

Cool muffins in pan for 5 minutes, then transfer to a wire rack to cool completely.