Add the blueberries to a blender or food processor and blend until completely smooth. Make sure there are no large pieces remaining so the mousse stays silky. Set the blueberry purée aside while you prepare the cheesecake base.

Place the softened cream cheese in a mixing bowl and beat it until it is completely smooth and creamy. Take your time with this step and scrape down the sides of the bowl as needed, as removing all lumps is key to achieving a true mousse-like texture.

Add the Greek yogurt, protein powder, sweetener, vanilla extract, and salt to the bowl with the cream cheese. Start mixing on low speed to help the protein powder blend in evenly, then gradually increase to medium speed as the mixture comes together.

Continue beating until the mixture looks light, fluffy, and fully combined. The texture should be airy and smooth, with no graininess from the protein powder and no streaks of yogurt or cream cheese remaining.

Add the blueberry purée to the cheesecake mixture and gently fold it in using a spatula. Use slow, careful motions to blend the color and flavor without deflating the mousse, stopping once it is evenly mixed or lightly swirled, depending on your preference.

Cover the bowl or portion the mousse into serving dishes, then place it in the refrigerator for 15–30 minutes. This short chilling time allows the flavors to meld and the texture to firm up slightly while staying soft and creamy.

Serve the mousse cold, either on its own or topped with a few fresh blueberries for garnish.