Matzo cake meal and coconut cream make this version of the decadent French classic a perfect Passover dessert your guests will devour.
Preheat the oven to 400 degrees. Place water, 6 tablespoons margarine, salt, and granulated sugar in a medium saucepan. Bring to a boil over medium heat. Add matzo meal and potato starch at the same time; stir vigorously with a wooden spoon. Mixture will become extremely stiff. Continue stirring for 4 minutes more.
Transfer mixture to the bowl of electric mixer fitted with the paddle attachment. With the mixer on medium speed, add eggs one at a time, fully incorporating each egg before adding the next. Mixture should be smooth and satiny, but stiff enough to form a mound when dropped from a spoon.
Fit a pastry bag with a plain coupler. Line two baking sheets with parchment. Fill pastry bag with profiterole batter. Pipe six 2 1/2-inch mounds on each pan, spacing 3 inches apart.
Transfer to oven, and bake until profiteroles are puffed and golden, about 25 minutes. Transfer to wire rack to cool.
Slice bananas in half lengthwise; cut each half into thirds. Heat a large skillet over medium heat. Add 2 tablespoons margarine and 1 1/2 tablespoons brown sugar. When margarine has melted and is sizzling, add half the bananas; brown them, about 3 minutes per side. Transfer bananas to a large shallow container to cool in a single layer. Melt another 2 tablespoons margarine with 1 1/2 tablespoons brown sugar in skillet; brown remaining bananas. Transfer to container.
To make the sauce, add orange juice, remaining 3 tablespoons brown sugar, and two pieces caramelized banana to empty pan. Whisk mixture over medium heat until thick and banana dissolves, about 1 minute.
Slice tops of profiteroles, leaving a small hinge. Insert 2 or 3 pieces of banana. Spoon 2 tablespoons whipped coconut cream onto banana. Serve with sauce.
The cooked profiteroles may be made up to 3 weeks ahead and kept in resealable plastic bags in the freezer, and the whipped coconut cream may be made up to 4 days ahead and kept in the refrigerator. Assemble profiteroles just before serving.