Ingredients

1/2 cup all-purpose flour 

1/2 cup packed dark-brown sugar 

1 1/2 ounces walnuts, broken into pieces (1/2 cup) 

1/4 cup old-fashioned oats 

1/4 teaspoon salt 

2 1/2 ounces (5 tablespoons) cold unsalted butter, cut into small pieces 

Preparation

Combine flour, sugar, walnuts, oats, and salt in the bowl of a mixer. Add butter, and beat on medium speed until mixture forms small clumps.