Maple Syrup Pie

1/2 cup cold water
1/4 cup all-purpose flour
1 cup maple syrup
1 egg, lightly beaten
2 tablespoons butter
1 pie crust, baked

Whisk water with flour until smooth; stir in syrup.
Stir in egg.
In a small heavy saucepan, cook over medium -low heat, stirring, until thick, 5-6 minutes.
Add butter & stir till melted.
Pour into baked pie crust.
Let cool.