• For the oat cookie:
  • 1/4 cup butter
  • 3 tbsp light brown sugar
  • 2 tbsp caster (superfine) sugar
  • 1 egg yolk
  • 5 tbsp bread flour
  • 2/3 cup oats
  • 1/4 tsp salt
  • Large pinch baking powder
  • Pinch of baking soda
  • For the pie shell:
  • 1 tbsp light brown sugar
  • 2 tbsp butter, melted
  • For the filling:
  • 1/3 cup caster sugar
  • 1/4 cup light brown sugar
  • 1/2 tsp salt
  • 1 tbsp milk powder
  • 1/4 cup butter, melted
  • 8 oz Nutella
  • 1/4 cup heavy cream
  • 1/4 tsp vanilla
  • 4 egg yolks
  • To decorate:
  • Caster (superfine) sugar, for dusting


  1. Preheat oven to 350 degrees. Grease and line a baking tray.
  2. Make the cookie: In a large mixing bowl, add the butter and sugars. Using an electric mixer, whisk for 2 to 3 minutes until light and fluffy. Add the egg yolk and beat for 1 to 2 more minutes, until pale and very light. Add the flour, oats, salt, baking powder and baking soda and slowly mix through until just combined. Pour the mixture onto the prepared baking tray, and spread it out to 1/4 inch thick. Bake for 15 minutes until browned on top and puffed up. Allow to cool fully, then transfer to a plastic bag and place in the fridge until needed.
  3. Make the base: Put the cooled cookie into a food processor and blitz to a fine crumb. Transfer to a mixing bowl and add the sugar and enough of the melted butter to allow you to bring it into a ball. Press mixture into a pie pan, pressing up the sides as well. Place on a baking sheet.
  4. Make the filling: Preheat the oven to 350 degrees. In the bowl of a stand mixer, add the sugars, milk powder and salt. Add the melted butter, and beat on low for 3 minutes. Add the Nutella, cream and vanilla and beat for another 3 minutes. Scrape down the bowl then add the egg yolks and mix until glossy and smooth.
  5. Pour mixture into the pie crust and place in oven for 15 minutes until brown but not set. Turn oven down to 325 degrees, opening the door for 1 minute to allow it to cool down. Close the door and cook for another 5 minutes. It should be wobbly in the middle but set around the edges. Transfer to a wire rack to cool, then wrap in plastic wrap and freeze for 3 hours or overnight.
  6. Defrost for at least 1 hour, then dust with caster sugar and cut into slices to serve.