Preheat oven to 350°. Cream together the butter and sugar. Add the egg yolks, lemon juice and lemon rind. Beat until smooth. Add the flour and baking powder and combine well. Set a 4 1/2″ x 14″ rectangular tart mold (with removable bottom) on a buttered baking sheet (or substitute a 9″ round tart pan with removable bottom). With your fingers, press 2/3 of the dough into the mold, covering the bottom and building up to a 1/2″ rim.
Combine the preserves and lemon juice and spread over the crust. On a floured surface, roll out the remaining dough until 3/16″ thick. Cut strips of dough 5/8″ wide and arrange them diagonally 1/2″ apart in a lattice pattern over the tart. Be sure no dough overhangs the rim. Bake for about 40 minutes. Cool thoroughly on a rack before removing the mold.
Do not refrigerate.