Preheat oven to 350 degrees F. Prepare brownie mix as package directs. On a greased pizza pan, baking stone or baking sheet, press batter into 12-inch circle. Bake 15 to 20 minutes. Cool.
Meanwhile, in small mixer bowl, beat cream cheese until fluffy. Gradually beat in sweetened condensed milk until smooth. Stir in pineapple or orange juice concentrate and vanilla. Chill this mixture thoroughly.
Spoon the cream cheese filling over brownie crust. Dip banana slices in fresh lemon juice or bottled lemon juice concentrate. Drain slices then arrange them over top of the pizza. Arrange strawberries and nuts over the top.
In small saucepan, over low heat, melt chocolate with margarine, drizzle over top. Chill until set, about 1 hour. Refrigerate leftovers.
Makes 1 (12-inch) pie.