Melt 5 tablespoons of unsalted butter in a microwave-safe bowl. Combine 1 ½ cups of graham cracker crumbs with the melted butter until moistened. Press mixture into the bottom and sides of a 9-inch springform pan.

Pour the contents of one 3 oz package of lemon Jell-O in a mixing bowl and add 1 cup of hot water. Stir until fully dissolved, about 2-3 minutes. Cool at room temperature for 20-30 minutes.

Beat 16 oz of softened cream cheese and ¾ cup of granulated sugar with an electric mixer until smooth and creamy, about 3-4 minutes. Add lemon zest and vanilla extract; mix until well combined.

Gradually pour the cooled lemon Jell-O mixture into the cream cheese mixture while blending on low speed until completely smooth, about 1-2 minutes.

Whip 1 cup of heavy whipping cream until soft peaks form, about 3-5 minutes. Gently fold into the lemon cream cheese mixture.

Pour the filling into the crust and spread evenly. Cover and refrigerate for at least 6 hours or overnight.

Remove cheesecake from the fridge, release from the springform pan, and garnish with whipped cream and lemon zest. Serve with lemon slices.