Prepare the Base:

In a medium saucepan, melt 1 cup of butter over low heat.

Stir in the brown sugar until it’s well combined.

Add the oats and cook over low heat for 2 to 3 minutes, or until ingredients are well blended.

Stir in the vanilla extract.

Press half of this mixture into the bottom of a greased 9×9-inch pan. Reserve the other half for the topping.

Prepare the Chocolate Layer:

In another saucepan, melt 1/2 cup of butter.

Add the chocolate chips and stir until the chocolate is melted and the mixture is smooth.

If you’re using peanut butter, stir it in now.

Pour the chocolate mixture over the oat layer in the pan, spreading it out evenly.

Finishing Touches:

Crumble the remaining oat mixture over the chocolate layer, pressing in gently.

Cover and refrigerate for 2-3 hours or until set.

Once set, remove from the refrigerator and cut into bars.