Step 1

Melt 6 Tbsp. butter in a small saucepan over medium heat. Let cool slightly.

Step 2

Crumble 10 graham crackers into the bowl of a food processor. Add 3 Tbsp. sugar, ¼ tsp. salt, and melted butter to bowl and process until mixture resembles wet sand.

Step 3

Transfer graham cracker mixture to a shallow 9" pie pan. Using a measuring cup, press firmly into bottom and up sides of dish. Freeze 20 minutes.

Step 4

Meanwhile, whisk ¾ cup heavy cream in a medium bowl until cream begins to thicken to the point you see ripples and stiff peaks begin to form, 3–5 minutes.

Step 5

Cut 4 limes in half and juice into a fine-mesh sieve set over a glass measuring cup (you should have about ½ cup juice). Pour lime juice into another medium bowl and whisk in 14 oz. condensed milk, 3 Tbsp. tequila, and remaining ¼ tsp. salt until smooth.

Step 6

Fold half of whipped cream into lime juice mixture, carefully folding under and over while turning the bowl. Add remaining whipped cream and continue to fold until no streaks remain.

Step 7

Remove pie pan from freezer and pour in filling. Using the back of a spoon, gently spread filling to edge of crust.

Step 8

Using a microplane, zest half of the remaining lime over pie.

Step 9

Freeze pie at least 8 hours, or preferably overnight.