This no-bake lemon pie has a lemon custard folded with sour cream in a graham cracker crust. No need to bake the crust or the pie itself. Chill for 4 hours before you serve.
In a medium bowl, stir together the graham cracker crumbs, brown sugar and mix well. Add the melted butter to the graham cracker mixture and toss to combine with a fork, ensuring that the mixture is evenly moistened.
Press the crust mixture evenly into the bottom and up the sides of a 9-inch pie pan, and press tightly with your hand or using the back of a measuring cup.
Place the pan in the freezer for at least 15 minutes while you prepare the filling.
For the sour cream lemon filling
In a pot, whisk together sugar, cornstarch, and salt. Add the lemon juice and milk; mix well. Heat the lemon filling mixture over medium heat until hot whisking constantly.
Remove the hot mixture from the heat and slowly pour about 1/2 cup into the egg yolks in a mixing bowl as you whisk. Pour more hot mixture a little bit at a time to temper the egg yolks.
Pour the hot filling mixture back to the pot and cook until it thickens and bubbles for 2 minutes, whisking constantly. Turn off the heat and immediately stir in the butter, whisking until smooth and creamy. Cool 15 minutes.
Whisk in the sour cream and lemon zest until completely combined. Pour into the pie crust and refrigerate for 4 hours, until chilled.
For the whipped cream
Pour whipping cream in a bowl, add powdered sugar and vanilla. Using a hand mixer, whip until stiff peaks form.
Put the cream in a piping bag and pipe it around the edges of pie. Or spread it on in an even layer on top and garnish with thinly sliced lemons.