Description
Halloween Monster Cookie Bars are soft, chewy, peanut buttery dessert bars loaded with old-fashioned oats, colorful Halloween M&M’s, semi-sweet chocolate chips, peanut butter chips, and candy eyeballs. These easy Halloween cookie bars are baked in one pan, making them perfect for Halloween parties, school celebrations, bake sales, and family treats.
Ingredients
Scale
- 2 cups all-purpose flour
- 1 1/2 cups old-fashioned oats
- 1 teaspoon baking soda
- 1/4 teaspoon salt
- 1/2 cup unsalted butter, softened
- 1/2 cup creamy peanut butter
- 1/2 cup granulated sugar
- 1/2 cup light brown sugar, lightly packed
- 2 large eggs, at room temperature
- 2 teaspoons vanilla extract
- 1 cup Halloween M&M’s, divided
- 1/2 cup semi-sweet chocolate chips, divided
- 1/2 cup peanut butter chips, divided
- Candy eyeballs, for decorating (optional)
Instructions
- Preheat the oven to 350°F (175°C). Line a 9-by-9-inch square baking pan with parchment paper, leaving an overhang for easy removal.
- In a medium bowl, whisk together the all-purpose flour, old-fashioned oats, baking soda, and salt. Set aside.
- In a large mixing bowl, beat the softened butter, creamy peanut butter, granulated sugar, and brown sugar until light and fluffy, about 2–3 minutes.
- Add the eggs and vanilla extract. Beat until well combined, scraping down the sides of the bowl as needed.
- Add the dry ingredient mixture to the wet ingredients. Mix on low speed until just combined, being careful not to overmix.
- Reserve about 1/4 cup of the M&M’s and 2 tablespoons each of the chocolate chips and peanut butter chips for topping. Fold the remaining candies and chips into the cookie dough.
- Transfer the dough to the prepared baking pan. Press it evenly into the pan using a spatula or the back of a spoon.
- Sprinkle the reserved M&M’s, chocolate chips, and peanut butter chips over the surface. Gently press them into the dough.
- Bake for 22–28 minutes, or until the edges are set and lightly golden and a toothpick inserted into the center comes out without wet dough.
- Remove the pan from the oven and gently press the candy eyeballs into the warm cookie bars, if using.
- Let the bars cool completely in the pan before lifting them out using the parchment paper. Cut into 16 squares and serve.
Notes
- Use softened butter and room-temperature eggs for a smooth, evenly mixed dough.
- Regular creamy peanut butter is recommended for the most consistent texture. Crunchy peanut butter can be used for extra crunch.
- Quick oats can replace old-fashioned oats, although the texture will be finer.
- Reserve some candies and chocolate chips for the topping to make the bars more colorful.
- Add candy eyeballs after baking so they retain their shape.
- Avoid overbaking. The center should be set but remain soft, and the bars will firm up as they cool.
- Allow the bars to cool completely before slicing for cleaner squares.
- Store in an airtight container at room temperature for up to 3 days.
- Freeze cooled bars in a freezer-safe container for up to 3 months. Thaw at room temperature before serving.
- For a peanut-free alternative, use an appropriate seed butter and verify that all other ingredients are safe for the intended dietary needs.
- Nutrition information is an estimate and will vary with ingredient brands, candy decorations, and serving size.
- Prep Time: 15 minutes
- Cook Time: 25 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American
Nutrition
- Serving Size: 1 bar (1/16 of recipe)
- Calories: 330 kcal
- Sugar: 23 g
- Sodium: 220 mg
- Fat: 16 g
- Saturated Fat: 7 g
- Unsaturated Fat: 8 g
- Trans Fat: 0.2 g
- Carbohydrates: 43 g
- Fiber: 2 g
- Protein: 6 g
- Cholesterol: 40 mg