These are chewy, rich and delicious. The brown butter is key.

• 2 cups flour
• 3 cups old-fashioned oats
• 3/4 tsp baking soda
• 1 tsp kosher salt
• 1 1/4 cups butterscotch chips
• 1 1/2 cups butter
• 1 1/2 cups brown sugar
• 2 eggs
• 3 tsp vanilla

Preheat oven to 350 degrees. Line a 9×13 inch pan with a foil sling (leave foil overhanging out of the pan to make removing the bars easier). Lightly grease the foil.

Combine flour, oats, soda and salt in a medium bowl. Place butterscotch chips in a large bowl.

In a small saucepan, melt the butter over medium heat. Continue to cook until the butter is brown and nutty – this could take up to 15 minutes or so. Pour browned butter over the butterscotch chips, scraping all the brown bits at the bottom of the saucepan and including them too. Whisk until butterscotch chips are melted. Whisk in brown sugar until smooth. Whisk in eggs and vanilla.

Stir flour mixture into butter mixture until well combined. Pour into prepared pan and smooth evenly.

Bake for 35 minutes, until the edges are brown and the center is just firm.

Let cook completely in the pan before lifting out and cutting into squares.

This recipe is adapted from America’s Test Kitchen.