Reserve ¼ cup of the heavy cream and set aside. Using an electric mixer and medium bowl, beat the remaining ¾ cup cream with the sugar on medium-high speed until soft peaks form, about 2 minutes.
1 cup heavy cream,, ⅔ cup sugar
In a separate bowl or a stand mixer fitted with the paddle attachment, beat the softened cream cheese on medium-high speed until smooth and creamy, about 2 minutes. Add the whipped cream mixture and beat on medium-low speed until combined, about 1 minute. Scrape down the sides and bottom of the bowl.
1 pound Philadelphia cream cheese (2 8-ounce containers),
Add the lemon juice, vanilla, and salt. Beat on medium-low speed for 1 minute, scraping the bowl again. Increase the speed to medium-high and beat until airy, about 1 minute. Add the lemon zest and beat just until incorporated.
1 ½ Tablespoons lemon juice from fresh lemon, 1 ¼ teaspoon vanilla extract, pinch salt, 1 teaspoon lemon zest
Pour the reserved ¼ cup cream into a microwave-safe measuring cup. Whisk in the gelatin and let it soften for about 3 minutes. Microwave on high for 10 seconds, then cool briefly, about 30 seconds. Stir if a film forms. Add the gelatin mixture to the filling and beat on medium speed until smooth and fully incorporated, about 30 seconds.
1 envelope unflavored gelatin,
Pour the filling into the prepared crust and spread evenly using an offset spatula. Refrigerate for 24 hours.