Equivalent of cracked fennel seed to ground fennel seed
I used a spice grinder to actually measure how much ground fennel I would get from 1TBS cracked. I got just over 2tsp ground. Therefore, 1/2 cup of cracked fennel is in a sense equivalent to about 6TBS ground. However, don't do it that way! Cracked fennel gives a little burst of flavor as you crunch the seed. Powdered fennel will strongly permeate the whole dish, and that much ground fennel will seriously overpower all other flavors. If the fennel is really necessary to the dish, and you can only get ground fennel, start with a single tablespoon, and then add more to taste. My guess would be that 2TBS will be plenty, but seriously, I wouldn't even try the substitution.