Instructions

• Preheat oven to 350°F. Line a 9×13-inch baking dish with foil and spray the foil with cooking spray.
• In a large bowl, combine 2 1/4 cups quick oats, 1 1/4 cups firmly packed brown sugar, 1 cup flour, and 1/2 teaspoon baking soda.
• Add 1 cup softened butter to the dry mixture. Use a hand mixer, pastry cutter, or your fingers to work the butter in until the mixture is crumbly and holds together when pressed.
• Measure out and set aside 2 cups of the crumbly mixture for the topping.
• Press the remaining crumb mixture evenly and firmly into the bottom of the prepared 9×13 pan to form the crust.
• In a separate small bowl, combine the entire (14-ounce) can sweetened condensed milk, 1/4 cup peanut butter, and 1/2 teaspoon vanilla. Mix with a hand mixer or whisk until smooth and well combined.
• Pour the sweetened condensed milk mixture over the pressed crust and spread it into an even layer.
• Sprinkle 12 ounces chocolate chips evenly over the sweetened condensed milk layer. If using, sprinkle 1/2 cup chopped nuts over the chocolate chips.
• Evenly crumble the reserved 2 cups of crumb mixture over the chocolate chips and nuts, then lightly press the top so it adheres.
• Bake in the preheated oven for 25–30 minutes, until the edges are golden brown (the center may still appear slightly soft).
• Remove from oven and let the bars cool completely in the pan on a wire rack before lifting out on the foil and cutting into bars.