Sheet Pan Halloween Cookie Bars

Ingredients

• 227 g (1 cup)unsalted butter, softened
• 150 g (¾ cup)sugar
• 200 g (1 cup)brown sugar
• 2eggs
• 5 ml (1 teaspoon)vanilla extract
• 250 g (2 cups)plain flour
• 5 g (1 teaspoon)bicarbonate of soda
• 3 g (½ teaspoon)salt
• 170 g (1 cup)chocolate chips
• 200 g (1 cup)Halloween M&M’s
• 40 g (¼ cup)Halloween sprinkles

Instructions

1. 1

   Prepare the pan

   Heat the oven to 180°C (350°F). Line a 23 × 33 cm (9 × 13-inch) baking pan with baking parchment and spray it with non-stick cooking spray.

2. 2

   Cream the sugars

   Put the softened butter, sugar and brown sugar in a bowl. Mix until creamy.

3. 3

   Add eggs

   Mix in the eggs and vanilla extract.

4. 4

   Add dry ingredients

   Mix in the flour, bicarbonate of soda and salt.

5. 5

   Fold in sweets

   Stir in the chocolate chips, M&M’s and sprinkles.

6. 6

   Spread the dough

   Spread the mixture evenly in the lined baking pan.

7. 7

   Bake the bars

   Bake for 20–25 minutes, or until cooked through.

What are Halloween cookie bars?

Cookie bars are cookie dough baked as one slab in a pan and cut into portions, rather than shaped into individual biscuits. This American-style version adds Halloween-coloured sweets and sprinkles to a familiar buttery, brown-sugar base.

Baking the dough together makes a handy treat for sharing at a party. The chocolate chips and sweets give each cut square a colourful mix of additions.

Nutrition and macros by portion

The nutrition label shows one serving as written: 430 calories, 3g protein, 59g carbs, 21g fat.

The flour and sugars provide most of the carbohydrates, while butter and chocolate chips contribute much of the fat; eggs add some protein. Pair a bar with fruit or a yoghurt-based snack if you want a more balanced plate.

Build the cookie base

Butter and sugars: softened butter mixes more easily with both sugars, helping create a creamy starting mixture. Mix until the texture looks cohesive before adding the eggs.

Flour mixture: stir the flour, bicarbonate of soda and salt together into the wet ingredients. Once the flour is incorporated, avoid prolonged mixing so the bars don’t become tough.

Keep the sweets intact

Chocolate and M&M’s: stir these through after the flour mixture is combined, distributing them across the dough without crushing the sweets.

Sprinkles: fold them in gently with the other additions. The dough will be thick, so scrape around the bowl to bring any unmixed pieces into the mixture.

Spread for even baking

Parchment: line the 23 × 33 cm pan and apply the non-stick spray as directed. The lining also makes it easier to lift or portion the baked slab once it has cooled.

Even layer: spread the dough across the pan rather than leaving a mound in the centre. A more even layer helps the edges and middle bake at a similar pace.

Check the bake

Timing: start checking at 20 minutes, then continue up to 25 minutes if needed. Pan material and oven differences can affect how quickly the bars bake.

Doneness: the recipe calls for the bars to be cooked through. Let them cool before cutting so the soft centre has time to settle and the squares are easier to lift.

Serve and share

Cut the cooled slab into 12 portions, as the recipe is written to serve 12. A sharp knife helps make cleaner squares through the chocolate and sweets.

Serve them on their own as a party sweet, or alongside fruit and unsweetened tea or coffee. The colourful toppings make them easy to identify on a Halloween dessert table.

Recipe notes & tips

• Bring the butter to room temperature so it creams smoothly with the sugars.
• Scrape down the bowl after mixing to catch any flour or butter left at the sides.
• Use baking parchment across the base of the pan for easier removal.
• Spread the dough into the corners for bars of a more even thickness.
• Allow the slab to cool before slicing for neater portions.

Variations

• Change the sweets: use another colour mix of M&M’s to suit a different celebration.
• Add nuts: fold in chopped nuts alongside the chocolate chips for extra crunch.
• Use white chocolate: replace some or all of the chocolate chips with white chocolate chips.
• Try different sprinkles: choose another shape or colour while keeping the same quantity.
• Make smaller squares: cut the cooled slab into more pieces for bite-sized party portions.

Common mistakes to avoid

• Butter too firm: let it soften before mixing so it combines smoothly with the sugars.
• Overmixing the flour: stop once the dry ingredients are incorporated to help avoid a tough texture.
• Uneven spreading: press the dough across the full pan so the middle is not much thicker than the edges.
• Skipping the lining: use baking parchment and non-stick spray as directed to help prevent sticking.
• Cutting while hot: let the bars cool first so they hold together better when sliced.

How to store

Keep the cooled bars in an airtight container at room temperature for up to 3 days. If you prefer them warm, heat an individual portion briefly in the microwave.

Frequently asked questions