In a heavy bottom saucepan melt the butter, brown sugar, and vanilla extract until the sugar is all dissolved.
Combine the oatmeal with the butter mixture and then press half of it into a prepared baking dish lined with parchment paper.
In a large bowl, melt the chocolate chips and peanut butter until smooth.
Spread 3/4 of the chocolate mixture over the oatmeal, then top with the reamining oatmeal. Drizzle the top with the remaining chocolate.