Bake flour at 350°F for 5 minutes, cool completely.
Melt butter and chocolate, mix in sugars, eggs, vanilla, then fold in dry ingredients.
Bake 25–30 minutes until moist crumbs form, cool fully.
Cream butter and sugars, add vanilla and milk, mix in flour and chips.
Press cookie dough over brownie layer, chill 30–45 minutes.
Heat cream, pour over chocolate, stir smooth for ganache.
Spread ganache on top and chill 1 hour until set.