Preheat your oven to 175°C (350°F) and line your baking pan with parchment paper, leaving some overhang for easy removal.
In a large mixing bowl, combine the peanut butter, brown sugar, and melted butter. Stir everything together until the mixture is smooth, creamy, and fragrant, about 2 minutes.
Stir in the vanilla extract, then add the quick oats. Mix well until the oats are fully incorporated and the dough feels thick but scoopable.
Gently fold in most of the chocolate chips, saving a handful for topping. The dough will be sticky but manageable with a spatula.
Press the mixture evenly into the prepared pan using a spatula or the back of a spoon, smoothing the top and ensuring it’s packed tightly.
Bake for 15 to 18 minutes, until the edges are golden brown and the kitchen smells warm and nutty with hints of melting chocolate.
Remove from oven and immediately sprinkle the remaining chocolate chips on top while the bars are still hot. Let them sit for about 10 minutes to allow the chocolate to melt slightly and set.
Transfer the pan to a cooling rack and let the bars cool completely for 30 minutes, which helps them firm up and makes slicing easier.
Once cooled, lift the bars out of the pan using the parchment overhang, then cut into squares with a sharp knife dipped in hot water for clean, neat edges.
Enjoy these chewy, rustic bars at room temperature or slightly warmed for a satisfying, gooey bite.