Quebecois Maple Cream Pie

¾ cup real maple syrup (dark amber)

2 ¼ cups heavy cream

4 egg yolks

1 egg

1 teaspoon salt

1 teaspoon vanilla extract

1 teaspoon distilled white vinegar

1 (9 inch) pie shell, baked

Preheat oven to 300 degrees F (150 degrees C). Place the pie crust in its plate in a large, shallow baking pan lined with foil in case of a boil-over.

Bring maple syrup to a boil in a heavy saucepan over medium heat, and cook for 5 to 7 minutes, to reduce syrup down by about one-quarter. Stir in cream, bring the mixture to a simmer, then remove from heat.

Whisk egg yolks and egg together in a large bowl. Very gradually add the cream mixture to the eggs, about 1/4 cup at a time, whisking constantly. Stir in salt, vanilla extract, and vinegar. Pour the batter into the prepared pie crust.

Bake until the pie is mostly set but jiggles slightly when moved, about 1 hour. Let cool before serving.