Ingredients:

  • 115g unsalted butter, softened
  • 75g light brown sugar, packed
  • 40g granulated sugar
  • 1 large egg yolk
  • 80g all-purpose flour
  • 120g old-fashioned rolled oats
  • 0.5 tsp salt
  • 0.25 tsp baking soda
  • 55g unsalted butter, melted
  • 20g light brown sugar
  • 200g granulated sugar
  • 150g light brown sugar
  • 30g Dutch-processed cocoa powder
  • 20g non-fat dry milk powder
  • 0.5 tsp salt
  • 115g unsalted butter, melted and cooled
  • 120ml heavy cream
  • 1 tsp vanilla extract
  • 4 large egg yolks

Instructions:

  1. Preheat oven to 350°F (175°C). In a mixer, cream 115g softened butter with 75g brown sugar and 40g granulated sugar until pale and fluffy.
  2. Add 1 egg yolk and mix. Fold in the flour, oats, 0.5 tsp salt, and baking soda until a dough forms.
  3. Spread the oat dough onto a parchment-lined baking sheet and bake for 15 minutes. Remove and let cool completely until brittle.
  4. Break the cooled cookie into pieces and pulse in a food processor into fine crumbs. Transfer to a bowl and mix with 55g melted butter and 20g brown sugar.
  5. Press the crumb mixture firmly into a 9-inch pie tin, covering the bottom and sides. Set aside.
  6. For the filling: Whisk together 200g granulated sugar, 150g brown sugar, cocoa powder, milk powder, and 0.5 tsp salt in a large bowl.
  7. Slowly whisk in 115g melted butter, heavy cream, and vanilla extract until fully emulsified. Whisk in 4 egg yolks one at a time.
  8. Pour the filling into the prepared crust. Bake at 350°F for 15 minutes, then reduce heat to 325°F and bake for an additional 30 minutes until the edges are set but the center still jiggles slightly.
  9. Cool the pie at room temperature for 2 hours, then refrigerate for at least 6 hours (or overnight) to allow the fudgy structure to set.