Start on a cold griddle (important) and pllace the chicken thighs skin-side down on the cold griddle.
Once all the thighs are on the griddle, THEN turn all burners to low heat.
This slow start lets the fat render out of the skin, which is what makes it crispy.
Cook for about 30–35 minutes total, mostly skin-side down.
As the fat renders out, you’ll see it pool on the griddle. Use your spatula to push that fat back toward the chicken so it continues frying in its own fat.
Around 15–20 minutes in, some pieces will naturally release from the griddle and turn golden brown. Flip only the ones that release easily.
Once flipped, cook for about 5 more minutes, or until the internal temperature reaches 170°F (76 C) or higher.
Remove from the griddle and enjoy.