Lightly grease an 8 inch, heat resistant, non metallic square baking dish.
Set aside.
In a small, heat-resistant, non-metallic bowl melt butter or margarine, uncovered, on full power 1 minute.
Place crunchy topping mix in a small bowl.
Add 1 1/2 table spoons of the melted margarine to topping and mix well.
Set aside.
In a medium sized bowl combine base mix, remainder of melted margarine and egg as package directs.
Mix thoroughly.
Spread batter evenly over the bottom of the baking dish.
Spread fruit filling over batter.
Sprinkle 2 tablespoons of rum over fruit filling.
Sprinkle crunchy topping over entire surface.
Heat, uncovered, on full power 5 minutes.
While cake is baking, beat egg whites until foamy.
Add cream of tartar.
Gradually add sugar, beating until meringue holds stiff peaks.
Add vanilla and the pinch of salt.
Spread meringue evenly over crunchy topping.
Heat, uncovered, on full power 2 minutes or until meringue is set.
Cool and then cut into squares.