Soften the cream cheese. Set it out at room temperature for 30–45 minutes. Soft cream cheese blends smoothly and prevents lumps.

Beat the cream cheese. In a medium bowl, use a hand mixer (or a sturdy whisk) to beat the cream cheese until completely smooth and fluffy, about 1–2 minutes.

Stream in the condensed milk. With the mixer on low, slowly add the sweetened condensed milk. Increase to medium and beat until silky, scraping down the bowl as needed. The mixture should be glossy and lump-free.

Add lemon juice. Pour in the lemon juice and mix just until combined. The acidity helps the mixture thicken slightly. If using, add a pinch of salt and the lemon zest for extra brightness.

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

Chill to set. Cover and refrigerate for at least 4 hours, or overnight for the cleanest slices. The filling will firm up as it chills.

Slice and serve. Use a sharp knife, wipe it clean between cuts, and serve chilled. Add berries or a dollop of whipped cream if you like.