Preheat the oven to 350 F or 180 C.

In an 8 inch by diameter oven safe pan or skillet, add your butter.

Brown the butter by cooking it over medium low heat for about 5 minutes or until it develops a light amber color and brown specks begin to appear on the surface. Do not stir, simply swirl the pan.

Let the butter cool COMPLETELY, about 30 minutes. Very important! In the meantime, you can remove the foam that has formed on top of the browned butter- this is optional 🙂

To the pan, add the sugar and mix using a rubber spatula or wooden spoon until smooth. If you do not want to follow the one bowl method, pour the browned butter into a bowl and follow same procedure.

Add the peanut butter, egg and vanilla and continue to mix.

Add the baking soda, salt and flour. The mixture will form a thick dough.

Fold in the oats and chocolate chunks. When they are evenly distributed through out the mixture, flatten it with the spoon or your hands until it coats the entirety of the pan. I also like to dab the surface of the cookie with a paper towel to remove any grease on the top.

Cover the handle of the pan with tin foil to prevent it from burning or overheating and bake for 15 minutes or until golden brown.

Cool slightly, then serve warm with some ice cream. It tastes great chilled too.