Melt butter and stir in flour, mixing well. Beat egg yolks with syrup and water. Add to butter-flour mixture and cook over boiling water until thick and creamy, stirring most of the time. Add walnuts and let cool. Pour into an 20 cm pie shell or divide into 6 individual tart molds lined with pastry.

As a variation, sprinkle the nuts on top instead of mixing them in the filling.

To make chiffon maple tarts, beat 2 egg whites until stiff, fold into cooked and cooled maple cream, then pour into baked tart shells.