Banana Frozen Yogurt

Line a baking sheet with wax paper. Peel and slice bananas into 1/4-inch-thick rounds. Spread the rounds on the baking sheet, cover with more wax paper and freeze until solid, 1 1/2 to 2 hours.

Combine the frozen bananas, sugar and cinnamon in a food processor and pulse until coarsely chopped. Combine yogurt (or buttermilk) and lemon juice; with the machine running, gradually pour the mixture through the feed tube. Process until smooth and creamy, scraping down the sides of the workbowl once or twice. (The frozen yogurt should be firm enough to be served directly from the food processor, but if it is a little soft, let it harden in the freezer for about 30 minutes.)