In a large mixing bowl, beat the softened cream cheese using a hand mixer or stand mixer on medium-high speed for 2–3 minutes. Continue until the cheese is completely smooth, airy, and free of any lumps.

Slowly pour the sweetened condensed milk into the cream cheese while mixing on low speed. Once added, increase speed slightly and beat until the two are fully combined and the mixture looks silky.

In a separate chilled glass or metal bowl, beat the heavy whipping cream until stiff peaks form (the cream should stand straight up when you lift the beaters).

Gently fold the whipped cream into the cream cheese mixture using a rubber spatula. Use a "down-across-up" motion to keep the air in the batter; do not use the electric mixer for this step, or the cheesecake will lose its stability.

Pour the filling into your graham cracker crust and smooth the top with a spatula. Cover loosely and refrigerate for at least 6 hours, though overnight is recommended for the cleanest slices.