Oat Cookie

1. Preheat the oven to 350F and line a large cookie sheet with parchment paper.
2. Using a hand or stand mixer with the paddle attachment, mix together the butter and sugars. Mix on medium-high speed for 2-3 minutes until fluffy and pale.
3. Scrape down the sides of the bowl and mix in the egg yolk on low speed. Increase to medium-high and beat for 1-2 minutes or until the sugar is fully dissolved and the mixture is pale yellow.
4. On low speed, add in the flour, oats, baking powder, baking soda, and salt. Mix until it just comes together.
5. As best as you can, spread the dough in an even layer on the parchment paper. It should be about 1/4 inch thick. I struggled with this a bit but found that if I applied pressure in small and short strokes (with a rubber spatula) that I was able to slowly spread it even. It won’t cover the entire pan. It’ll just look like a big cookie blob.
6. Bake for 15 minutes or until it has golden brown edges and a dull top. Cool completely before using. If you’re making it ahead, you can crumble it up into an air-tight container and store in the fridge. It will keep up to 1 week.

Crust

1. After the cookie has cooled, crumble it up into a food processor along with the brown sugar and salt. Pulse until it resembles wet sand. In Christina’s recipe, she says that if you don’t have a food processor, to “fake it till you make it and crumble the oat cookie diligently with your hands.”
2. Transfer the crumbs to a bowl and add the melted butter. I mixed it lightly with a fork then got my hands in there to fully incorporate it. It should be wet enough to where it can form a ball. If it doesn’t, add 1 to 1 1/2 tablespoons of butter at a time until you get there. I had to add a whole extra 1 1/2 tablespoons to get mine to the right consistency.
3. Evenly divide the oat crust between two 10-inch pie pans (Christina uses disposable aluminum pans you can find at the grocery store). Press in firmly to make sure the bottom and edges are covered. Use the crusts immediately or wrap well in plastic wrap and store in the fridge for up to 2 weeks.

Filling

1. Preheat the oven to 350F and have the room temperature oat cookie crusts ready.
2. For this part, Christina says you MUST use a stand mixer with a paddle attachment for this. It makes all the difference in creating that smooth and silky filling. But I think if you’re careful, a hand mixer can do the job. Just take it slooooowww. Be careful to not whip ANY air into this pie.
3. Combine the sugar, brown sugar, milk powder, corn powder, and salt in the bowl of the stand mixer. Mix on low to evenly blend.
4. Add in the melted butter and mix on low for 2-3 minutes until the dry ingredients are moist.
5. Add in the heavy cream and vanilla and continue to mix on low for 2-3 minutes until white streaks from the cream have completely disappeared. Scrape down the bowl.
6. Add in the egg yolks a couple at a time, mixing on low until it’s just combined. It should be glossy and smooth.
7. Evenly divide the filling into the two pie crusts. They should be 3/4 of the way full. Bake for 15 minutes then open the oven door and reduce your temperature to 325F. When your oven reaches that temperature, close the door and bake the pies for another 5 minutes. They should be a little jiggly in the very center of the pie but not on the edges. If they’re still too jiggly, leave them in for an additional 5 minutes.
8. Take the pies out of the oven and transfer to a cooking rack. Then freeze your pies for at least 3 hours or overnight. This is what gives you that dense center. Transfer to the refrigerator to thaw for at least 1 hour before serving. Serve cold.
9. Dust powdered sugar all over the top. Now welcome to heaven as you enjoy your first bite!