Preheat oven to 350F and spray a regular 6 hole donut pan.
In a bowl whisk together your egg and sugar, add in your sour cream, yogurt, vanilla and mix well.
Stir in your flour, baking powder and salt.
Divide into your 6 donut holes, do not fill right to the rim or you might not have enough batter for 6 and they rise up.
Bake in the oven for approx 18 minutes.
Let cool 5 minutes, for glaze mix your icing sugar and milk together on a flat plate, then dip donuts in glaze, it will be enough to just lightly glaze them and add a little sweetness, icing is optional though.