My mom taught me how to make this refreshingly tart treat. Can’t beat a recipe with 4 ingredients.

For a slightly sweeter, less tart pie, reduce the lemon juice to 2/3 cup; for a bracing, old-time pucker, use a full 3/4 cup and pack your lemons full of juice. If you prefer a more traditional baked crust, you can pop the graham cracker crust into a 350°F oven for 6–8 minutes to toast lightly, then cool completely before filling; it adds a little crunch and a toasty flavor. A simple garnish of thin lemon slices or a light sprinkle of grated lemon zest on top before chilling makes the pie look extra special without adding more ingredients. If you’re making this ahead for a picnic or church supper, freeze the pie for 1–2 hours before traveling so it stays cold longer; just let it soften in the refrigerator before serving. You can also divide the filling among small glass dishes or jars for individual icebox desserts using the same four ingredients, pressing a little crust into the bottom of each and spooning the lemon filling over the top. However you serve it, keep the pie well chilled, as the creamy filling is at its best straight from the icebox.