Pre-heat oven t0 180°C (356°F). Spray a 6-count donut case with a few 1 calorie sprays.
Combine all the donut ingredients except for the lemon zest in a medium bowl until smooth and lump-free.
Fold in the lemon zest until fully combined. Spoon or pipe the mixture evenly into the donut molds.
Bake the donuts until a toothpick inserted into the center comes out clean - about 15 minutes.
Cool the donuts in the donut case for 2-5 minutes before transferring to a wire rack to cool completely.
Meanwhile, prepare the frosting by mixing the cream cheese, 0 calorie icing sugar and lemon juice until smooth. Spoon and spread the frosting onto the donuts and serve.