Drain pineapple well and save the juice.
Sprinkle pineapple in greased 9 x 13 x 2 inch pan. (Smaller pan makes the roll too thick.)
Scatter zucchini over pineapple.
Sprinkle with brown sugar and pat it down with your hand.
Mix sugar and egg yolks.
Stir in pineapple juice and extract, then flour, salt, and baking powder.
Beat egg whites until stiff, fold into batter.
Spoon batter over zucchini mixture in pan, smooth the top.
Bake at 375° for 15 to 18 minutes, or until cake tests done.
Do not overbake.
Loosen cake from sides of pan.
Turn it out, upside down, on clean dishtowel sprinkled with powdered sugar.
Trim off any crisp edges of cake.
While still hot, roll the cake, starting at the 9 inch end (pick up edge of cloth to start it rolling).
Wrap it in the cloth until it is cool.
Slice and top with whipped cream for an elegant dessert.
Best eaten the day you bake it.