In a separate bowl mix the applesauce, oil, egg, egg yolk, sugars, and vanilla.
Mix the wet ingredients into the dry ones until just combined.
Fold in blueberries and lemon zest. If you want to you can toss the blueberries with flour first to help keep them from sinking to the bottom of the muffins.
Scoop batter into muffin tins and bake for 20-25 minutes or until a toothpick comes out clean.