1. Preheat the oven to 350°F (180°C) and grease your mini Bundt cake molds twice with cooking spray or melted butter using a pastry brush.

2. In a large mixing bowl, beat the softened butter, powdered sugar, and lemon zest with an electric mixer at medium speed for 1-2 minutes until light and creamy.

3. Add the egg and vanilla extract, then mix until well combined.

4. In a separate small bowl, combine the milk and lemon juice and let it sit for a few minutes to slightly curdle (this creates a buttermilk effect).

5. Alternate adding the dry ingredients (flour, salt, and baking powder) and the milk mixture to the batter, starting and ending with the dry ingredients. Gently fold them in using a kitchen spatula until just combined.

6. Stir in the sour cream at the end, making sure the batter is smooth.

7. Pour the batter into the prepared Bundt cake molds and smooth the tops.

8. Bake for approximately 30 minutes, or until the cakes are golden on top and a toothpick inserted into the center comes out clean.

9. Let the mini Bundt cakes cool in the molds for 30 minutes to 1 hour before carefully removing them and placing them on a cooling rack to cool completely.

Lemon Glaze:

1. In a small bowl, whisk together powdered sugar and lemon juice until smooth and pourable.
2. Drizzle the glaze over the cooled mini Bundt cakes before serving.