Begin by lining an 8-inch or 9-inch square baking dish with parchment paper, allowing the edges to hang over for easy removal later.

In a large saucepan over medium heat, melt together ½ cup of butter and ¾ cup of brown sugar. Stir consistently for about 3-5 minutes until the mixture is smooth.

Stir in 2 cups of rolled oats into the saucepan with the buttery mixture. Lower the heat and cook for 3-4 minutes, mixing thoroughly.

Pour half of the oat mixture into the prepared baking dish, pressing it down firmly to form a solid bottom layer.

In a microwave-safe bowl, combine 1 cup of chocolate chips and ½ cup of peanut butter. Heat in 30-second intervals, stirring until fully melted.

Pour the melted chocolate and peanut butter mixture over the first oat layer in the baking dish, spreading it evenly.

Top the chocolate-peanut butter layer with the remaining oat mixture, pressing down gently to create an even surface.

Refrigerate your assembled bars for at least 2-3 hours, or preferably overnight, until they are firm to the touch.

After chilling, remove the bars from the baking dish using the parchment paper overhang. Slice into squares or rectangles.