Chill your tools. Place a mixing bowl and beaters in the freezer for 5 minutes. Cold equipment helps the whipped cream thicken quickly.

Make the whipped cream. Add the heavy cream, powdered sugar, and vanilla to the chilled bowl. Beat on medium-high until you get soft, billowy peaks. Don’t overbeat.

Mix the lemon base. In another bowl, whisk the sweetened condensed milk, lemon juice, lemon zest, and a pinch of salt until smooth. The mixture will thicken slightly as the lemon reacts with the milk.

Fold it together. Gently fold two-thirds of the whipped cream into the lemon mixture. Use light strokes to keep the filling airy.

Fill the crust. Pour the filling into the graham cracker crust and smooth the top with a spatula.

Top and decorate. Spread or pipe the remaining whipped cream over the top. Add extra zest, a few thin lemon slices, or crushed graham crackers for a simple finish.

Chill to set. Refrigerate for at least 2 hours, or until firm enough to slice. For the cleanest slices, chill 4 hours or overnight.

Slice and serve. Use a sharp knife dipped in warm water and wiped dry between cuts for tidy pieces.