Reduce the blueberries on the stovetop! Cook over medium heat to help remove some of the liquid until you have about 1½ tablespoons of reduced blueberries. I like to give them a quick blend to make the mixture smoother and remove any pieces or chunks that can make piping tricky.
Whip the egg whites. In a clean, dry glass or metal bowl (this is key, don’t use plastic!) whip the egg whites with an electric hand mixer for 4–5 minutes, until stiff peaks form.
In a small bowl, add the yogurt, cornstarch, lemon juice and blueberry purée. Stir to combine.
Gently fold the blueberry mixture into the whipped egg whites.
Add the mixture to a zip top bag and cut a small hole in the bottom corner, or use a piping bag.
Pipe small dollops onto a parchment-lined baking sheet.
Bake at 200°F for 50–60 minutes, until the yogurt melts feel dry and lift easily from the parchment paper. They should crumble when you press them together between your fingers!
