Preheat the oven to 350°F and grease a standard 12-cup muffin tin with butter or cooking spray. Process the cottage cheese in a blender or food processor until it is completely smooth with no visible curds remaining. Zest the lemon and set it aside. Take 1 tablespoon of flour from your measured amount and toss it with the blueberries until they are lightly coated; this helps keep them from sinking during baking.

In a medium bowl, whisk together the remaining flour, baking powder, baking soda, salt, and ground cinnamon until the leavening agents are evenly distributed throughout the flour.

In a large bowl, whisk the melted, cooled butter and sugar together until just combined. Add the eggs one at a time, whisking gently after each addition, then stir in the vanilla extract. Using a spatula, fold in the blended cottage cheese and lemon zest until the mixture is smooth and uniform.

Pour the wet ingredients into the bowl of dry ingredients. Using a spatula or wooden spoon, fold everything together gently until no streaks of dry flour remain — the batter will look slightly lumpy, which is exactly right. Overmixing at this stage builds gluten and leads to tough muffins. Carefully fold in the flour-coated blueberries without crushing them.

Divide the batter evenly among the prepared muffin cups, filling each about two-thirds full. A small ice cream or cookie scoop makes portioning easy and consistent. Bake in the preheated 350°F oven for 20 to 22 minutes, or until a toothpick inserted into the center of a muffin comes out clean or with only a few moist crumbs.

Remove the tin from the oven and allow the muffins to rest in the pan for 5 to 10 minutes so they can set before being moved. Run a thin knife around the edge of each muffin to loosen it, then gently turn them out onto a wire rack to finish cooling completely.