In a medium-sized mixing bowl combine egg, egg yolk, and buttermilk. Whisk to combine. Add oil, vanilla, and vanilla bean seeds. Whisk again to combine.
Stir wet ingredients into dry ingredients. Stir until just combined. Fold cranberries into batter. Fill a ziplock bag with the filling and clip the corner of the bag.
Squeeze batter into donut pan until 2/3 to 3/4 full. Bake 8 to 10 minutes or until a toothpick inserted comes out clean. Don’t over bake. Let cool 5 minutes in the pan.