Get ingredients together and make sure you have everything.
Chop the jalapeño and serrano chili peppers and place them in a small saucepan over medium heat. Add 3/4 cup of olive oil. Stir in the cayenne, paprika, and black pepper. Steep over for about 12 minutes. Add the garlic and continue to steep for 3 minutes longer. Allow the oil to completely cool. Place in a bowl or jar and cover. Put the cooled oil in the refrigerator and allow it to sit overnight.
Rinse the chicken under cold water and pat dry with paper towels. Using a heavy chef’s knife and kitchen shears, cut the bird into 8 pieces: 2 legs, 2 thighs, 2 breasts, and 2 wings. Reserve the backbone for stock. This video shows how to butcher a whole chicken.
Strain the chili oil into a large bowl. Slice 2 lemons and add them to the bowl. Season with salt. Coat chicken with the oil and place the pieces in a large zip-top bag. Place the bag inside a baking dish to catch spills and refrigerate for at least 4 hours.
Preheat your oven to 500°F. Heat a cast-iron or other heavy oven-proof skillet over medium-high heat until it’s quite hot, approximately 5 minutes. Meanwhile, remove the chicken from the chili oil and pat it dry. Season the chicken with salt and pepper.
Pour enough olive oil into the skillet to just coat the bottom. Put the chicken, skin-side down, in the hot skillet. Cook until the skin is crisp and golden, about 8 to 10 minutes. Turn the chicken skin-side up.
Put the skillet in the oven and roast the chicken for about 20 minutes, or until the internal temperature of the thigh reaches 170°F when checked with a digital meat thermometer.
Remove the chicken to a serving platter and juice the half lemon all over the top. Grind more pepper over the chicken and allow it to rest for 10 minutes.
Serve the spicy chicken while warm with your favorite sides.