Preheat your oven to 350°F (175°C) and grease a 12-cup muffin tin with butter or cooking spray.

In a blender or mixing bowl, combine the melted butter, granulated sugar, eggs, whole milk, all-purpose flour, fresh lemon juice, lemon zest, vanilla extract, and salt. Blend until smooth for about 1-2 minutes.

Pour the batter into the prepared muffin cups, filling each about two-thirds full.

Bake for 28 to 32 minutes until golden on top and slightly jiggly in the center.

Cool in the muffin tin for about 10 minutes, then transfer to a wire rack to cool completely.

Chill in the refrigerator for at least 1 hour before serving.