Soak flax seed powder in warm water from cookie dough in a small bowl for 10-15 minutes. Set aside.
In a double boiler or a smaller pan settled on a water bath, melt butter and chocolate together.
The water in the bath should be simmering.
Continue stirring until both chocolate and butter are fully melted.
Remove it from flame.
Alternatively you can melt butter and chocolate together in a microwave in 30 secs spurts till they are melted together.
Add sugar, followed by the remaining bowl of flax seed mixture and vanilla extract to the chocolate mixture.
Add cocoa powder and salt and mix well using a whisk.
Using gentle folding, add the flour to the batter until combined.
Now pour the brownie batter in the prepared pan. If required, spread out evenly using a spatula.
Using a tablespoon, dump the cookie dough on top of the brownie layer.
The dumping can be uneven allowing little brownie batter o show in places.
Press down gently.
Bake for 25-30 minutes or till done.
Let it cool completely in the pan over a wire rack.
Using the overhang of butter paper, pull out the cookie brownie bars.
Preferably let the brownies cool overnight and then slice them with a plastic knife instead of a steel one, it is easier to slice the brownies. Serve warm with ice-cream and sauce on the side.
Slice them and enjoy with a cup of tea or coffee.
You can store them in refrigerator in an air-tight container.