Frozen Maple Mousse Pie - cooking recipe

Ingredients

4 large egg yolks
1/2 cup pure maple syrup
2 tablespoons dark rum
1 1/3 cups heavy cream, chilled
1 (9 inch) prepared graham cracker crusts

Preparation

Add 2 inches of water in a medium saucepan; bring the water to a bare simmer.
Whisk the egg yolks and maple syrup together in a medium stainless steel bowl and place the bowl over the simmering water, making sure that the bottom of the bowl doesn't touch the water.
Heat the egg/maple mixture, whisking constantly, until it registers 160\u00b0 on an instant-read thermometer.
Remove the bowl from the pan; using an electric mixer, beat the egg/maple mixture for about 5 minutes or until it is cool and thick; stir in the rum.
In another medium mixing bowl, whip the heavy cream, using an electric mixer, until soft peaks form.
Gently fold the whipped cream into the egg/maple mixture.
Scrape the filling into the prepared pie crust.
Cover the pie with plastic wrap and refrigerate until the filling is completely set (at least 6 hours and up to 1 day)--I don't know why this pie is called frozen.