Make the meringue In a medium saucepan, bring 2 inches of water to a simmer. In the bowl of a stand mixer, whisk the egg whites with the sugar. Set the bowl over the saucepan (the bowl should not be touching the water) and cook, whisking constantly, until the sugar is completely dissolved and an instant-read thermometer inserted into the egg whites reads 160°, about 5 minutes. Attach the bowl to a stand mixer fitted with a whisk attachment and beat at medium-high speed until the meringue is thick, white and glossy, 5 to 7 minutes. Meanwhile, unwrap the pie and carefully invert onto a platter or cake stand; discard the plastic wrap. Using an offset spatula, swirl the meringue all over the pie. Freeze until set, about 20 minutes.