Preheat your oven to 350°F (175°C). This ensures the cupcakes bake evenly and rise properly.

Line a cupcake tin with paper liners.

In a large mixing bowl, cream together the softened butter and granulated sugar using an electric mixer on medium speed until light and fluffy, about 3-4 minutes. This incorporates air into the mixture, helping the cupcakes to rise.

Add the eggs one at a time, mixing well after each addition. This helps to emulsify the mixture, ensuring a smooth batter.

In a separate bowl, combine the flour, baking powder, baking soda, and salt. Whisk together to evenly distribute the leavening agents.

In another bowl, mix the buttermilk, lime juice, lime zest, tequila, and vanilla extract.

Gradually add the dry ingredients to the butter mixture, alternating with the wet ingredients, starting and ending with the dry. Mix until just combined; do not overmix to keep the cupcakes light and fluffy.

Divide the batter evenly among the cupcake liners, filling each about ⅔ full.

Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center comes out clean. This ensures the cupcakes are fully cooked.

Remove from the oven and allow to cool in the tin for 5 minutes before transferring to a cooling rack to cool completely.

In a large mixing bowl, beat the softened butter with an electric mixer on medium speed until creamy.

Gradually add the powdered sugar, mixing on low speed to prevent a sugar cloud. Once incorporated, increase to medium speed.

Add the lime juice, lime zest, and vanilla extract, mixing until smooth and fluffy. If the frosting is too thick, add a teaspoon of milk to reach desired consistency.

Once the cupcakes are completely cool, frost them generously with the lime buttercream using a spatula or piping bag.

Optional: Rim the edges of the cupcakes with coarse sea salt for an authentic margarita experience.

Top each cupcake with a slice of lime for garnish.