Preheat the oven to 350 degrees. Position your oven rack in the middle of the oven.
Prepare a baking sheet by lining it with parchment paper.
In a stand mixer at medium speed, cream together the 6 Tablespoons of butter with the brown and white sugars.
It will take about 3 minutes for this mixture to become light and fluffy. Scrape down the sides of the bowl.
Beat in the egg and vanilla for another 2 minutes.
Reduce the speed to low, and mix in the rolled oats, flour, salt, baking powder, and baking soda. Scrape down the
sides, and be sure that this is well mixed.
Spread this cookie dough about ¼ inch thick on the prepared baking pan. It does not have to fill the whole pan, as
we will just be breaking up this big cookie later.
Bake for 15 minutes or until the top is turning golden.
Remove the pan from the oven and place it on a cooling rack.
While this is cooling we will make the filling.
Using the paddle attachment on your standing mixer, combine the white sugar, brown sugar, milk powder, and salt
at low speed.
Add the melted butter and mix until all ingredients are wet. Scrape down the sides of the bowl.
Mix in the heavy cream and vanilla, scraping down the sides as needed. It will take 2- 3 minutes for these
ingredients to be fully incorporated.
Make sure you keep the speed set to low as you add in the egg yolks. You will mix this until the mixture is glossy.
(about 3 minutes)
Set this filling mixture aside.
When the cookie is completely cooled, break it up into pieces which you will put in a food processor. Add the
remaining 2 Tablespoons of softened butter and add this to the food processor. Pulse until crumbly and mixed
Press these oatmeal cookie crumbs into the bottom and up the sides of your pie dish. (A 9-10 inch glass pie dish
Place the pie dish onto a baking sheet.
Pour the filling into the pie dish.
Carefully move the baking sheet containing the pie pan to the middle rack of the oven.
Bake for 15 minutes.
Turn the oven temperature down to 325 and bake for 15 more minutes. The pie should be fairly brown on top. It
may still be a little jiggly. If it is very jiggly, give it 5 more minutes.
Remove the pie from the oven. Place the pie pan on a cooling rack and allow it to cool for ½ hour. Then wrap it with
tin foil and place it in the freezer (for at least 2 hours, or overnight). Move the pie from the freezer to the fridge 1
an hour before you are planning to serve it.
Dust it with icing sugar before serving.