Ingredients

  • Cookie
  • 3 ounces all-purpose flour (2/3 cup plus 1 tablespoon)
  • 1/8 teaspoon baking powder, scant
  • 1/8 teaspoon baking soda, scant
  • 1/4 teaspoon salt
  • 1/2 cup softened butter (1 stick)
  • 2 1/2 ounces light brown sugar (1/3 cup)
  • 1 1/4 ounces white sugar (3 tablespoons)
  • 1 egg
  • 3 1/2 ounces rolled oats (scant 1 cup)
  • Crust
  • 1/4 cup butter (1/2 stick)
  • 3/4 ounce light brown sugar (1 1/2 tablespoons)
  • 1/8 teaspoon salt
  • Filling
  • 10 1/2 ounces white sugar (1 1/2 cups)
  • 7 ounces light brown sugar (1 cup less 3 1/2 tsp)
  • 1/4 teaspoon salt
  • 3/4 ounce powdered milk (1/3 cup plus 1 teaspoon)
  • 1 cup butter, melted (2 sticks)
  • 7/8 cup heavy cream (3/4 cup plus 2 tablespoons, scant)
  • 1 teaspoon vanilla extract
  • 8 egg yolks
  • powdered sugar, for garnish

Method

  • Preheat oven to 375°F.
  • In a large bowl, sift together flour, baking powder, baking soda and salt.
  • In a stand mixer with the paddle attachment (or a large mixing bowl with a hand-held electric mixer), beat together butter, brown sugar and white sugar until light and fluffy. Add egg and beat until combined.
  • With mixer running on low, add flour mixture in small increments until fully combined. Add oats and mix until combined.
  • Spread mixture into an unlined, ungreased 9x13 baking sheet. Bake in preheated oven 20 minutes until golden brown and set. Cool a few minutes in pan, then turn out onto a rack until cool to the touch. Lower the oven to 350°F while the cookie cools.
  • Crumble the cooled cookie into the workbowl of a food processor. Add butter, brown sugar and salt. Pulse until combined (a clump of the mixture should hold together when pinched together). Divide the mixture between 2 10" pie pans, pressing into an even, thin layer on the bottom and sides. (The top edge will be ragged.).
  • In a large bowl, whisk together white sugar, brown sugar, salt and powdered milk. Add melted butter, cream and vanilla and whisk until smooth. Whisk in egg yolks one at a time. Be careful not to incorporate too much air.
  • Divide the filling evenly between the two pie crusts. Bake one pie at a time for 15 minutes, then reduce heat to 325°F for 10 minutes, until the filling is golden brown but still jiggly (like a pecan pie). Place pie pans on a rack to cool.
  • Refrigerate the pies until well-chilled; the filling will be gooey. Dust with powdered sugar before serving.