Preheat oven to 350°F. Lightly spray a 9-inch pie dish with cooking spray.
Melt butter in a microwave-safe bowl and let cool about 5 minutes so the crust doesn’t turn greasy. Process graham crackers in a blender or food processor until finely crushed. Measure 1-3/4 cups crumbs into a large bowl. Add sugar and salt, then stir in cooled butter until evenly combined.
Press mixture firmly into the pie dish, first up the sides and then across the bottom. Use the flat bottom of a measuring cup to compact the crust. Bake 8 minutes, then remove and let cool.
In a stand mixer or with a hand mixer, beat sweetened condensed milk, egg yolks, 3/4 cup freshly squeezed lemon juice, lemon extract, and salt on medium speed for 2 to 4 minutes until smooth.
Pour the filling into the crust and smooth the top. Bake 12 to 17 minutes, until mostly set with a slight jiggle in the center. If the crust browns too quickly, loosely cover the edges with foil. Remove and cool on a rack for 30 minutes.
Refrigerate for at least 1 hour (cover if longer than an hour).
Combine cream, powdered sugar, and vanilla. Beat at high speed with a stand or hand mixer until soft peaks form, about 1 to 4 minutes. Spread whipped cream over the pie if serving right away, or add to individual slices if planning for leftovers. Garnish slices with lemon zest, lemon slices, or mint if desired. Serve chilled.
Cover leftovers tightly and refrigerate.
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Notes
Note 1: Look for pure lemon extract in the baking aisle. If unavailable, omit it. The pie will still be delicious but slightly less lemony.Note 2: For clean slices, run a knife under hot water, dry it, slice once, then repeat.Storage: Keep at room temperature up to 2 hours. Store in the fridge in an airtight container for 2 to 4 days. This pie does not freeze and thaw well.