Preheat the oven to 350F.

Whisk the egg whites with the cream of tartar until soft peaks have formed.

Add the sweetener and whisk again until stiff peaks have formed.

Gently fold in the chopped blueberries and chocolate chips.

Spoon the mixture onto a baking pan lined with a silicone mat. This recipe makes about 18 cookies.

Place in the preheated oven and immediately turn the oven OFF. Leave the cookies in the oven for at least 2 hours with the oven door closed. Leave overnight to harden if necessary.