Whip the cold heavy cream with a hand mixer or stand mixer fitted with the whisk attachment on medium-high speed for about 4–5 minutes. Stop when the cream forms firm, upright stiff peaks and no longer falls over at the tip.
Beat the softened cream cheese and granulated sugar on medium speed until completely smooth, scraping the bowl as needed. The mixture should look creamy with no visible cream cheese flecks before the remaining filling ingredients go in.
Add the confectioners’ sugar, sour cream, lemon juice, and vanilla extract, then beat on medium-high speed for 2–3 minutes. Keep mixing until the filling is smooth and cohesive, with no large lumps remaining.
Fold the whipped cream into the cream cheese mixture using a silicone spatula or the mixer on low speed. Use broad, gentle sweeps until no white streaks remain, stopping as soon as the filling looks evenly airy.
Spoon the filling into the chilled crust and level the surface with an offset spatula. A smooth top helps the cheesecake settle evenly as it chills.
Cover the pan tightly with plastic wrap or aluminum foil and refrigerate for at least 6–8 hours, or up to 2 days. A 12-hour chill gives the filling the firmest set and the cleanest resistance when sliced.
Run a knife around the inside edge of the springform pan, then release and remove the collar before cutting. A soft release sound and intact sides signal that the cheesecake is fully set.
Cut with a clean, sharp knife and wipe the blade between slices before serving with desired toppings. Each slice should hold a crisp crust edge and a smooth, creamy center.