Preheat oven to 325°F (163°C). Grease a small baking dish or ramekin.
Add cottage cheese, cream cheese, eggs, and 2 tbsp blueberries to a blender.
Blend until smooth and creamy.
Pour batter into the prepared dish.
Top with the remaining 1 tbsp blueberries.
Bake for 30–35 minutes, until the edges are set and the center is slightly jiggly.
Cool at room temperature for 20–30 minutes.
Refrigerate for at least 2 hours before serving.