From the Star-K website
One should be mafrish Challah when kneading 2.6 lbs. of flour, which on average is equivalent to 8.667 cups of flour. However, a bracha is not recited for this amount. If one kneads a smaller amount of flour, one is not mafrish Challah.
There are two customs as to the amount that must be kneaded to require a bracha. Some individuals recite a bracha when kneading 3.675 lbs. or more of flour (on average, 12.25 cups). Many only recite a bracha when kneading 4.95 lbs. of flour (i.e. almost the entire contents of a 5 lb. bag of flour – on average, 16.5 cups of flour). Individuals should follow their family custom.
Now a website weighs nothing and virtual cookies also have no weight so Challa would not be taken for this.