Key Lime Pie

Name: Key Lime Pie
Prep time: 25 min
Cook time: 25 min
Total time: 50 min
Cuisine: American
Ingredients: 10 whole graham crackers; 1/2 teaspoon kosher salt; 3 tablespoons granulated sugar; 2.5 ounces melted butter, cooled; 14 ounces sweetened condensed milk; 4 egg yolks; 4 ounces freshly squeezed key lime juice (from approximately 20 key limes); 1 tablespoon key lime zest, plus more for decoration; 6 ounces heavy cream; 2 tablespoons confectioner's sugar; 1/4 cup mascarpone cheese (optional)