I have been buying chicken gizzards from Good Earth Farms - they ship them frozen in 5 lb bags.
Each gizzard has a nice chunk of yellow fat on it which I cut off and place into a cast iron skillet.
I turn the burner to low to let the fat render slowly. After a while the chunks of fat will begin to shrink and turn brown and you will start getting a bunch of liquid fat.
When the chunks of fat start getting crispy and there are no raw pieces left, I start pouring the fat off into a jar. I find that the remaining chunks render better if there is less liquid fat in the skillet. Keep repeating this process until the chunks of fat are nothing but crispy little pieces - which taste amazing.
Since I had a batch of Chicken Bone Broth going while I was doing this, I took the gizzards without the fat and added them to my broth.
An easier way to do this would have been to just add the gizzards with the fat to the Chicken Bone Broth, and then to skim the fat off the broth once it is done. However, I like the taste of the rendered fat better when I make it in a cast iron skillet and I love cracklings.
I pour the chicken fat into a glass measuring cup then pour it from the measuring cup through a strainer into the jar I am going to store the fat in. From a 5 lb bag of gizzards I usually get anywhere from 10 to 16 oz of liquid chicken fat.
And now you can eat the cracklings.