Cut the prepared chicken hearts in half. Or, if using chicken thighs, cut into 1-inch pieces. Season with ½ teaspoon salt.
Add the buttermilk to a medium bowl and add the chicken. Toss to coat and ensure all of the chicken is covered. Cover and marinate in the refrigerator for 2 to 4 hours.
Remove the chicken from the fridge. Set a clean plate nearby and line a baking sheet with paper towels.
Combine the flour, remaining 1 teaspoon salt, baking powder, garlic powder, and paprika in a shallow bowl and whisk.
Let excess marinade drip off a few chicken pieces for just a second or two and then add them to the flour mixture. Toss to coat completely. Place on the plate and repeat with the remaining chicken.
Add one inch of oil to a wide, deep, heavy-bottomed pan and heat to 350°F. Let the chicken rest while the oil heats up.
Once hot, add about half of the chicken to the oil, stirring gently with a spider or slotted spoon. Let fry until golden brown and crispy, 4 to 5 minutes total, flipping as needed. Set on the cooling rack and sprinkle with salt.
Repeat with the remaining chicken and enjoy warm.
