Using three shallow containers, fill the first with the cornstarch, the second with the egg and buttermilk (whisked to combine,) and the third with the flour and seasonings.
One thigh at a time, dredge first in the cornstarch, then the egg mix, and finally into the flour mix making sure the chicken is fully coated. Set aside on a sheet tray until ready to fry.
In a dutch oven, heat the oil until a thermometer reaches 350F. Fry the chicken one at a time, flipping only once if not submerged, until an internal temperature of 160F is reached. Carefully remove and let rest on a rack. Repeat with the remaining chicken thighs.
For the waffles, combine all the bisquick ingredients in a mixing bowl and whisk to combine. Ladle into a hot waffle iron and cook until crispy and golden brown, about 4 minutes.
Serve with the warmed syrup of your choice and butter.