Ingredients
Method
- Preheat your oven to 350°F (175°C). Lightly grease a 9x13-inch baking pan with cooking spray or line it with parchment paper for easy removal.
- In a large mixing bowl, use an electric mixer to cream the softened butter, brown sugar, and granulated sugar until the mixture is light and fluffy, about 2-3 minutes.
- Beat in the eggs one at a time, then mix in the vanilla extract until well combined.
- In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, mixing on low speed just until no streaks of flour remain.
- Fold in the chocolate chips, peanut butter chips, and mini marshmallows using a spatula. The dough will be thick.
- Spread the cookie dough evenly into the prepared pan. Drizzle the chocolate syrup over the top in a zigzag pattern.
- Bake for 25-30 minutes, or until the edges are golden brown and the center is just set. Let the bars cool in the pan on a wire rack for at least 10 minutes before cutting into squares.
- Transfer the bars to a wire rack to cool completely, then serve warm or at room temperature.
Nutrition
Notes
For extra richness, use dark chocolate chips or add a handful of chopped walnuts. Store bars in an airtight container at room temperature for up to 5 days. You can make the dough ahead and refrigerate it for up to 24 hours before baking. Avoid overmixing the dough to keep the bars tender. For cleaner cuts, chill the bars for 20 minutes before slicing.