Preheat your oven to 350°F (175°C). Grease a standard muffin tin or line it with cupcake liners.

In a large bowl, whisk together the sweetened condensed milk, lemon juice, eggs, melted butter, and vanilla extract until smooth and well combined.

Gently fold in the self-rising flour and lemon zest. Mix until just combined, being careful not to overmix.

Pour the batter evenly into the prepared muffin cups, filling each about ¾ full.

Bake for 18–22 minutes, or until the tops are lightly golden and the centers are set. A toothpick inserted into the center should come out clean.

Allow the pies to cool in the muffin tin for about 10 minutes before transferring them to a wire rack to cool completely. Serve chilled or at room temperature.

Dust with powdered sugar for a pretty finish. Top with a dollop of whipped cream and a lemon slice for extra flavor and presentation.