To begin, preheat your oven to 325 degrees. Line a standard muffin pan with papers and set it aside.
In a bowl whisk or sift together the flour, baking powder, and salt. Set that aside for the moment.
In your mixing bowl, beat together the unsalted butter and sugar. Beat those together for a couple minutes until super fluffy. Beat in the room temperature eggs, one at a time, completely mixing in the first before adding the second.
Now you’ll add in some flavorings. You’ll need to zest the two limes. Add about 3/4 of the zest into the mixing bowl, along with the vanilla and tequila. Then you’ll need to juice a lime and a half. Hang on to the last half though, you’ll need it later for the frosting.
Add the juice from the lime and a half into the mixing bowl as well and mix it all in. Add in half of your flour mixture, combining completely and making sure to scrape the side of the bowl with a rubber spatula.
Pour half of the buttermilk in and mix thoroughly. Follow with the remaining flour mixture and then the last of the buttermilk, fully mixing each time. Scoop the batter into the muffin pan, dividing it evenly between all of the cups.
Bake for about 22-25 minutes or until very lightly golden and a test done in the center with a toothpick. Remove the cupcakes to a cooling rack and cool completely.
Now for the frosting. In your cleaned mixing bowl, beat the room temperature butter until super fluffy. Mix in the powdered sugar and beat until completely combined.
Grab that remaining lime half and squeeze in a tablespoon of lime juice. Add in the tequila. Beat until completely mixed together. If the frosting is too soft, beat in a little more powdered sugar.
Put the frosting into a piping bag and frost the cupcakes. Top the frosted cupcakes with the reserved lime zest.
And the final touch, a tiny pinch of flaked sea salt.