Combine pineapple and banana in an 8-inch square dish; toss well. Cover and freeze at least 1 hour.
Combine frozen fruit, yogurt, milk, and vanilla in container of an electric blender; cover and process until smooth, stopping once to scrape down sides. Serve immediately.
Cooking Light Low-Fat, Low-Calorie Quick and Easy Cookbook
Find recipes with ingredients that you have on hand.