Preheat your oven to 450 degrees F.
Unroll the crust on a work surface. Using floured fingertips, seal any tears in the dough. Sprinkle dough very lightly with flour. Place the dough in a 9-inch-diameter ceramic or glass pie dish. Fold overhang under and form smooth top edge.
Crimp edge decoratively. Pierce bottom and sides of crust all over with a fork.
Bake the crust 10 minutes until the crust is deep golden around the top edge and light golden on the bottom. Set aside to cool.
While the crust cools, make the filling. Lower the temperature of the oven to 375 degrees F.
In a medium saucepan, bring the milk and lemon zest to a boil over medium heat. Remove the pan from the heat and allow the mixture to cool for 5 minutes.
In a large bowl, mix together the egg yolks, sugar and flour (mixture will be thick). Pour the milk mixture into the bowl and whisk until smooth. Return the mixture to the saucepan and whisk constantly over medium-low heat until smooth and thick, about 6 to 7 minutes. Remove the pan from the heat and stir in the butter. Whisk in the vanilla, thyme and lemon juice until smooth. Let cool slightly.
Pour the filling into the cooled pie crust. Bake for 20 – 25 minutes. (If the pie crust begins to get too dark, cover the edges with aluminum foil.) The center will be loose and will set up as it cools. Place in the refrigerator for 2 hours until completely chilled.
Before serving, make the whipped topping. Place the heavy cream in a medium bowl. Using an electric hand mixer, beat the cream until soft peaks form. Add the vanilla and powdered sugar. Beat until well combined. Serve the vanilla whipped cream with the pie.