To prepare the crust, preheat oven to 350° F. Combine butter and sugar in a sauce pan over medium heat. Stir frequently until the butter has melted and the sugar loses its gritty consistency.
Mix in finely ground tortilla chips, stirring until well combined. Transfer crumbs to a 9 to 9/ 1/2-inch tart pan with a removable bottom or a 9-inch pie pan. Working carefully -- the mixture will be quite warm -- distribute crumbs evenly and firmly press them into the bottom and up the sides to form a crust (a small measuring cup helps, although fingers work best for the sides).
Bake crust until it smells fragrant and has just started to brown, about 15 minutes. Remove from oven and set aside.
For the filling, whisk together sugar and eggs in a medium saucepan. Add lime zest, juice, tequila, triple sec, and salt; whisk until smooth. Cook over medium-low heat, stirring constantly, until mixture thickens to the consistency of loose pudding, about 10 minutes. Reduce heat to low and whisk in butter, a few slices at a time, until completely melted and smooth.
Pour filling through a fine strainer into prepared tart crust. Jostle tart pan until the filling is evenly distributed. Cool at room temperature for about 30 minutes and then chill in the refrigerator for at least four hours until set.
For the whipped cream, combine cream, confectioners’ sugar, tequila, and triple sec in a large bowl. Beat with an electric mixer or whisk by hand until peaks form. Spoon or pipe atop the tart. Garnish with lime slices. Sprinkle with coarse salt before serving if desired.