In a large bowl or Ziploc bag, combine the buttermilk, olive oil, garlic, herbs, and hot sauce. Add the chicken and toss to coat.
Cover and refrigerate the chicken in the marinade for at least 30 minutes or up to overnight.
Preheat oven to 400°F. Line a large, rimmed baking sheet with foil and place a wire rack on top. Spray the wire rack with nonstick cooking spray. Set aside.
Remove the chicken from the marinade, letting any excess marinade drain from the chicken. Discard the buttermilk marinade.
Pat chicken dry with paper towels. Place the chicken skin-side up in a single layer on the prepared baking sheet. Brush each piece of chicken with olive oil; season liberally with salt and pepper on all sides.
Roast the chicken, uncovered, until it’s golden brown on top and an instant-read thermometer registers 165°F when inserted into the thickest part of the meat (not touching the bone), about 40-45 minutes for chicken thighs and smaller pieces, and about 55-60 minutes for larger chicken breasts. Tent the chicken loosely with foil if the skin starts to get too dark before the meat is cooked through.
Let the chicken pieces rest for at least 5 minutes. Garnish with chopped fresh herbs just before serving, if desired.