Preheat oven to 350°F; butter a 10 or 11 inch tart pan with removable bottom.
For pastry: Cream butter with sugar in large bowl; mix in walnuts; blend in egg and almond extract; stir in flour until completely incorporated; press into pan (bottom and side); refrigerate 30 minutes; bake until golden-brown, 15-20 minutes; cool to room temperature.
For custard: Beat yolks, sugar, cornstarch and vanilla in medium bowl until pale and thick; heat milk in medium saucepan; beat milk into yolk mixture until smooth; return to saucepan and whisk over medium heat until very thick, about 5 minutes; return to bowl and beat, adding butter 1 tablespoon at a time and beating until melted before adding next tablespoon; beat until cool; refrigerate until chilled.
To whip cream: Beat whipping cream with icing sugar until soft peaks form.
To assemble: Spread custard evenly over crust; starting from outer edge, arrange strawberries in concentric circles, placing as close together as possible; refrigerate 30 minutes; melt jelly (don't forget - jelly is seedless, if you haven't got any, use apricot jam) in small saucepan over low heat; brush gently over berries, covering completely; refrigerate at least 2 hours; Serve with whipped cream, if desired.