For the Donuts: Preheat oven to 350 degrees F. Coat the wells of a donut pan with nonstick cooking spray.
In a medium bowl, combine flour, sugar, baking powder, salt and poppy seeds. In another bowl, whisk together buttermilk, butter, vanilla, egg and lemon zest. Pour wet ingredients into dry ingredients and mix until well combined. Do not over-mix. Fill each mold almost to the top with batter.
Bake for 15-17 minutes, or until a toothpick inserted into one donut comes out clean.
Remove pan from oven and let donuts cool completely before glazing.
For the Glaze: Whisk all ingredients in a medium bowl, starting with 2 Tablespoons milk or cream. If desired, add more milk to thin glaze, or more powdered sugar to thicken. To glaze donuts, dip tops into glaze and place on a wire rack to set.
Store refrigerated in an airtight container up to 3 days.
For this recipe and more, visit www.thecomfortofcooking.com