Smoothies can be calorie- and fat-laden milkshakes in disguise, or they can be refreshing and nourishing treats that cool you down on a hot day.

Frozen bananas are a perfect ingredient for smoothies that fall into the latter category. If you buy too many bananas, peel the extra-ripe ones, halve them and tuck into a freezer bag. When you’re ready for a smoothie, combine about a cup of milk (skim, low-fat, soy … whatever you prefer) and half a banana in the blender. For a super-creamy smoothie, use a whole banana. Yesterday I added a few fresh strawberries and a squeeze of honey. Process until smooth, and enjoy.

Other fruits can sub for or go in with the banana. Reach for your favorites — frozen blueberries, peaches and mangoes are all good. You also can add chocolate syrup for a chocolate-banana smoothie, or a small scoop of sherbet, regular or frozen yogurt or ice cream. It’s hard to go wrong when concocting a smoothie.

For an all-fruit smoothie, try this recipe from a new cookbook, “Green Black Red: Recipes for Cooking and Enjoying California Grapes,” by Susan Volland (Chronicle Books, $16.95).

GREAT GRAPE SMOOTHIE

Yield: 2 servings

1 cup seedless grapes

1/2 cup frozen cherries

1/2 cup frozen strawberries

1/2 cup peeled and sliced orange

1/2 cup sliced banana

Combine all ingredients in the jar of a blender; blend until smooth. Pour into two 12-ounce glasses and serve.