Ingredients
GOOEY CHOCOLATE FILLING:
- 2 cups semi-sweet chocolate chips
- One 14-ounce can sweetened condensed milk
- 2 teaspoons vanilla extract
COOKIES:
- 1 cup unsalted butter, at room temperature
- 1 cup dark brown sugar
- 1/2 cup granulated white sugar
- 1 large egg
- 1 large egg yolk
- 1 tablespoon vanilla extract
- 2 cups all-purpose flour
- 1 cup quick-cooking or old-fashioned rolled oats
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- 1 teaspoon kosher salt
- 1 1/2 cups milk chocolate chips
- 1 1/2 cups white chocolate chips
Instructions
Preheat oven to 350 degrees F. Lightly butter a 9x13-inch pan and line with parchment paper, allowing enough overhang on the long side to lift the bars from the pan.
For the gooey chocolate filling:
Place the chocolate chips and condensed milk in a small saucepan over the lowest possible heat and cook, stirring constantly, until the chocolate has melted and the mixture has thickened, 3 to 5 minutes.
Turn off the heat, add vanilla, and stir until smooth. Set aside to cool to room temperature.
For the cookie dough:
Place the butter and sugars in a large bowl. Beat with an electric mixer until smooth and creamy. Add the egg, egg yolk and vanilla. Beat well.
Whisk together the flour, oats, baking powder, baking soda and salt in a medium bowl.
Add to the butter mixture. Beat until everything is well incorporated, scraping down the sides of the bowl as needed.
Stir in the milk chocolate chips and the white chocolate chips.
To make the bars:
Using half of the batch of cookie dough, place dollops into the prepared pan and press down lightly to even it out.
Pour the cooled chocolate mixture over the dough and then add small dollops of the remaining dough on top. Don't worry if the dollops don't completely cover the chocolate mixture. Just spread it together as much as you can, and let some chocolate peek through.
Bake until lightly browned, 20 to 25 minutes. Set aside to cool completely.
Refrigerate to make cutting the bars easier and then enjoy at room temperature or return to the refrigerator.