Combine flour, white sugar, baking powder, salt, cinnamon, and nutmeg in a small bowl.

In a large bowl, mash bananas. Mix in eggs, milk, and margarine until smooth. Stir in flour mixture.

Heat 1/2 inch oil in a deep fryer or heavy-bottomed pan to 375 degrees F (190 degrees C). Drop batter by spoonfuls into hot oil, and cook, turning once, until browned, 2 to 8 minutes. Drain on paper towels and dust with confectioners' sugar.