Green is a strange color for banana muffins. Can you guess the secret ingredient in these Frankenmuffins? (Toni L. Sandys/The Washington Post)

This is a week in which looking scary comes with sweet rewards. The same is true of the recipe for Frankenmuffins, a snack that doesn’t look appealing because of its unusual green color. But take a bite, and you will be surprised by a delicious banana flavor. You’re probably thinking, “Why is a banana muffin green?” It’s from the spinach that colors the batter but doesn’t leave a trace of vegetable flavor. Friends in the cafeteria might not be begging for a taste of your “scary” muffin. You can either let them in on the secret and be ready to share, or smile and keep the treat all to yourself.

Frankenmuffins

You’ll need more than one 12-well muffin pan; if you have only one, you can bake in batches. Cover and refrigerate the reserved batter until 15 minutes before you use it.

MAKE AHEAD: The muffins can be stored in an airtight container at room temperature for up to 2 days. They can also be frozen for up to 1 month. Defrost in a microwave on HIGH for 10 seconds before serving. Adapted from the October 2014 issue of Family Fun magazine.

Adult help: Yes

Kitchen gear: Muffin pans, paper liners, measuring spoons and cups, bowl, whisk, blender, spatula.

Hands-on time: 15 minutes

Total time: 37 minutes

Makes: 16 muffins

Ingredients

1 cup all-purpose flour

1 cup whole-wheat flour

3/4 cup sugar

2 teaspoons baking powder

1/2 teaspoon baking soda

1/2 teaspoon kosher salt

11/2 teaspoons ground cinnamon

1/4 cup canola oil

3/4 cup regular or low-fat milk

9 ounces fresh baby spinach (6 packed cups)

1 large banana, cut into chunks (1/2 cup packed)

2 teaspoons vanilla extract

Steps

- Preheat the oven to 350 degrees. Line 16 wells in two standard-size muffin pans with paper liners (preferably Halloween-appropriate) or grease them with cooking oil spray. (Or bake in batches; see the headnote at left).

- Whisk together the all-purpose and whole-wheat flours, the sugar, baking powder, baking soda, salt and cinnamon in a mixing bowl.

- Combine the oil, milk and spinach in a blender; puree until smooth, then add the banana and the vanilla extract. Puree until smooth (and green). Pour into the flour mixture; use a flexible spatula to stir until no dry spots of flour are left.

- To make things easy, pour some of the batter into a large measuring cup with a spout; use that to pour enough batter to fill each muffin well two-thirds full. Bake for about 22 minutes, or until a toothpick inserted in the center of each muffin comes out clean.

- Transfer the muffin pan to a wire rack to cool for 15 minutes, then turn the pan over so the muffins fall out. Turn them right side up to cool completely before serving or storing.

Nutrition | Per muffin (using low-fat milk): 140 calories, 3 g protein, 24 g carbohydrates, 4 g fat, 0 g saturated fat, 0 mg cholesterol, 95 mg sodium, 2 g dietary fiber, 11 g sugar

Recipe tested by Toni L. Sandys; e-mail questions to food@washpost.com

Try another seasonal snack

Hungry for another Halloween-inspired recipe? Baked pumpkin seeds are a classic. But instead of adding salt, we have a sweet version. Cinnamony Pepitas — pumpkin seeds are called pepitas in Mexico — are crunchy, delicious and easy to make. Find the recipe at wapo.st/pepitas.