In a small pot, melt butter with brown sugar until sugar dissolves. Stir in vanilla and oats. Cook over low heat 3 minutes more, stirring frequently.
Pour half the oat mixture into the baking dish and press down.
Over low heat, melt chocolate together with peanut butter stirring occasionally. Spread over oats reserving about 2 Tablespoons of the chocolate pb sauce.
Spread remaining oat mixture over the top and gently press down. Drizzle with remaining chocolate-peanut butter. To make drizzling easier, spoon chocolate pb into the corner of a ziplock bag, snip the corner off, and squeeze onto the bars.
Allow to cool and then refrigerate 2-3 hours before slicing and devouring.
Recipe by Jellibean Journals at https://jellibeanjournals.com/no-bake-chocolate-peanut-butter-squares/