Preheat the oven to 350F (180C) degrees.
Line a cookie sheet with parchment paper. Spoon/sprinkle the flour on top in an even layer. **I typically sprinkle about 1 ½ cups, even though you'll only use 1 ¼ cup in the cookie dough since I typically lose a bit of the flour in transferring it between the cookie sheet and the bowl**
Bake the flour in the oven for 10 minutes. Remove from the oven and turn it off.
In a medium bowl beat the butter, brown sugar, and white sugar until smooth.
Mix in the vanilla extract, followed by the milk.
Measure out 1 ¼ cups of your heat treated flour. If it's lumpy, sift the flour. Then mix into the cookie dough.
Mix in the mini chocolate chips.
Press the cookie dough on top of the cooled brownies, forming an even layer.
Place in the fridge for about 30 minutes for the cookie dough layer to firm up.
When ready to slice, remove the brownies from the pan using the overhang of the parchment paper/tin foil. Place on a cutting board.
Slice with a sharp knife. These brownies are very rich, so you only need a small piece.