Preparation

Preheat oven to 350°F (175°C). Spray a 9-inch (20cm) springform pan with vegetable oil spay. Using an electric mixer, cream margarine and sugar on high speed until fluffy. Add eggs, one at a time and mix until smooth. Mix in banana puree, sour cream, rum and vanilla extract on medium speed. In a small bowl, stir flour, baking soda, salt and cinnamon together. Gradually add flour mixture to banana mixture and blend just until smooth. Pour batter into springform pan. Bake for about 30 minutes, until lightly browned and a toothpick inserted in the center comes out clean. Do not overbake. Let cake cool for about 10 minutes and remove sides from spring form pan. Sprinkle powered sugar over cake before serving.