Combine the flour, salt, and shortening. Add the vinegar and the egg to the water, blend into the flour mixture, and mix well. Chill dough for a day before rolling out.
Melt the butter and add the flour, the boiling water, and the maple syrup. Bring to a boil, stirring constantly. Pour into a piecrust and bake at 200o C (400o F) for about 35 min.