Preheat oven to 350. Spread the flour over a small cookie sheet. Toast it in the oven for 5 minutes. Remove from oven and let cool. This is a necessary step to treat the flour so it is safe to eat.
In a food processor, pulse oreo cookies until finely ground. Add butter and process until it’s distributed and you have wet crumbs.
Press the crumbs into a 9” tart pan, on the bottom and up the sides. Bake it for about 7 minutes, then let it cool on the counter. Once it’s cool to touch, place it in the freezer.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugars on medium until light and fluffy, about 7-9 minutes. Add the vanilla and salt and beat to combine.Add the toasted flour and chocolate and beat on low to combine. Pour in the heavy cream and whip the mixture on high for about 5 minutes, until it’s very light and airy.
Dollop the whipped cookie dough into the frozen shell and smooth it down. Set in the fridge.
Warm the heavy cream in a saucepan until the sides just bubble. Pour it over the chopped chocolate and stir, then let it sit for a few minutes. Stir until you have a smooth and glossy ganache. Pour ganache over the cookie dough into an even layer.
Once the ganache is mostly set, sprinkle the flaked sea salt over it.
Let the ganache firm up in the fridge for about two hours before serving.
Store in the fridge or freezer.