Grease a 9-x-9-inch baking pan and line the bottom and sides with parchment paper, set aside.
In a medium pot melt butter. Once melted add in brown sugar and oats cooking on low for 4 to 5 minutes.
Add in vanilla.
While the oats are cooking, melt the chocolate chips with the peanut butter in the microwave in 30-second intervals until the chocolate chips are melted.
Pour half of the oat mixture into the prepared pan, pressing to distribute evenly.
Pour the melted chocolate-peanut butter mixture on top of the oat layer.
Top with the remaining oat-mixture. Gently press the oat-mixture into the chocolate-peanut butter mixture.
Cover the pan and let the mixture cool for 2 hours, after 2 hours it should be very firm.
Remove the bar from the pan by lifting up the parchment paper. Remove the paper and cut the bar into smaller bars.
