Chocolate Coconut Squares

Preheat oven to 350 °F. In a food processor pulse biscuits or crackers until finely ground. Melt butter and in a large bowl stir together with crumbs, coconut, and salt until combined. Firmly press crumb mixture evenly onto bottom of a 9-inch square baking pan and bake in middle of oven until golden, about 15 minutes. Cool crust completely in pan on a rack. Chop chocolate. In a double boiler or a metal bowl set over a saucepan of barely simmering water melt chocolate, stirring until smooth. Remove top of double boiler or bowl from heat and cool chocolate 15 minutes. In a small bowl lightly beat yolks. In a saucepan heat cream over moderate heat until it just boils and whisk 1/2 cup into yolks, whisking constantly. Add mixture to remaining cream and cook over moderate heat, whisking, until an instant-read thermometer registers 160 °F. Whisk custard into chocolate until just smooth and pour evenly over crust, smoothing top with a small metal offset spatula or rubber spatula. Chill confection, covered, at least 4 hours, or until firm. With a sharp thin knife cut confection into 36 squares. (Squares keep, layered between sheets of wax paper in an airtight container and chilled, 1 week.) Using star shapes cut out of parchment paper as a stencil, dust squares with confectioners' sugar.