To make the raspberry topping: In a blender or food processor, blend the raspberries and water until smooth. Strain the liquid through a fine mesh strainer into a small saucepan; discard the raspberry seeds. , Add the sugar and lemon juice to the saucepan, stirring to combine. Cook over medium heat for 2 to 3 minutes until the mixture boils, then reduce to a simmer. Continue to cook the mixture, stirring constantly, for about 6 to 8 minutes, until it has thickened and a line drawn in the bottom of the saucepan with a spatula holds its shape for a few seconds. You should have a scant 1/2 cup (about 140g) of topping., Remove the raspberry topping from the heat and allow it to cool while you prepare the rest of the no-bake cheesecake. The topping can also be made up to 5 days in advance and stored, covered, in the refrigerator until ready to use. , To make the crust: Stir together the graham cracker crumbs, confectioners’ sugar, and salt. Add the melted butter and mix until thoroughly combined. , Press the crumbs into the bottom and up the sides of a 9" pie pan at least 1 1/4" tall. Chill the crust in the refrigerator while you make the filling. , To make the no-bake cheesecake filling: In the bowl of a stand mixer fitted with the flat beater attachment or working with an electric hand mixer in a large bowl, combine the cream cheese, vanilla, lemon emulsion or zest, and salt. Mix at low speed until completely smooth and no lumps remain. Stop and scrape down the sides of the bowl as needed. , Add 3/4 cup (85g) of the confectioners’ sugar and the sour cream; mix until smooth. Transfer the cream cheese mixture to another large bowl., In the same bowl used to make the cream cheese mixture (no need to clean it out first), combine the cream with the remaining 1/4 cup (28g) confectioners’ sugar. Use the whisk attachment to whip on medium-low speed until stiff peaks form. , Using a whisk, fold the whipped cream, about 1/3 at a time, into the cream cheese mixture until no streaks remain., Remove the crust from the refrigerator and transfer the filling to the pan. Use a small offset spatula or the back of a spoon to evenly spread the filling over the crust., Pour the raspberry topping over the filling, spreading it evenly over the entire surface, from edge to edge. , Chill the no-bake cheesecake in the refrigerator for at least 8 hours, preferably overnight. (A cake carrier or large container is the easiest way to cover the cheesecake while it chills without disturbing the topping.) When ready to serve, slice the cheesecake and serve chilled with additional raspberries, if desired. , Storage information: Store any leftover no-bake cheesecake, covered, in the refrigerator for several days; freeze for longer storage. To serve from frozen, thaw in the refrigerator overnight before slicing and serving the next day.