Preheat the oven to 300°F. Line a baking sheet with parchment paper.

Drain the cottage cheese well by tilting the container and pouring off excess liquid or using a fine mesh strainer.

Blend the drained cottage cheese with an immersion blender or in a food processor until completely smooth.

In a clean, dry bowl, beat the egg whites and cream of tartar with a hand mixer on high speed until stiff, glossy peaks form.

In a separate bowl, whisk together the egg yolks, blended cottage cheese, powdered sweetener, vanilla bean paste, lemon zest, and cornstarch until smooth and fully combined.

Gently fold the yolk mixture into the whipped egg whites using a spatula, turning the bowl and lifting from the bottom to keep as much air as possible.

Carefully fold in the blueberries just until evenly distributed without deflating the batter.

Use a 1/4 cup measuring cup to scoop mounds of batter onto the prepared baking sheet, spacing them about 2 inches apart.

Bake for 25 to 30 minutes, until the rounds are golden brown on top and feel set and springy to the touch.

Let the cloud bread cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely before serving.