Preheat your oven to 350°F and spray a 12-count muffin pan with non-stick spray.
In a medium bowl, whisk the flour, baking powder, baking soda, and salt.
In a large bowl, whisk the sugar, melted butter, eggs, vanilla, lemon juice, whole milk, and sour cream. Mix until smooth. Add the dry ingredients to the wet ingredients and mix until smooth. Whisk in the poppy seeds and pour the batter evenly into the prepared muffin pan, filling all the way to the top.
Bake in the preheated oven for 15-17 minutes. A toothpick inserted into the center should come out clean. Let cool slightly before removing the muffins from the pan.
Make the glaze: In a medium bowl, whisk the powdered sugar, lemon juice, milk (or cream), vanilla extract, and salt. If the glaze is too runny you can add more powdered sugar. Or, if it's too thick you can add more milk.
Drizzle the glaze over the muffins once cooled. Store muffins in an air-tight container at room temperature for 1 week.