In a large mixing bowl, whisk together the flour, baking soda, baking powder, salt, and poppy seeds.
In a medium mixing bowl, stir together the melted, cooled butter and the sugars. Then stir in 3/4 teaspoon vanilla extract and two eggs. Then stir in the sour cream and milk.
Stir the wet ingredients into the dry, until a thick batter forms (like cake batter).
Spoon the batter into a loaf pan lined with parchment paper.
Bake at 350°F for 45-48 minutes, until a toothpick inserted into the center comes out clean.
While the loaf cools, make the glaze. Whisk together juice from half a orange (about 2 heaping tablespoons) with 1/4 teaspoon vanilla extract and the powdered sugar. Drizzle over the poppy seed bread before serving.