Preheat oven to 400F.
Salt chicken on both sides.
Place chicken skin side down on a cold cast iron pan and add to medium-high heat. Cook until skin is extremely golden (about 10 minutes). Remove from pan.
Cut green tops and root end off leeks and slice the middle white portion lengthwise. Thinly dice the green tops. Wash and dry both parts well.
Add long middle strips of leeks to the hot frying pan over medium-high heat. Press down with a pot lid and cook for 2 - 3 minutes until slightly golden/charred.
Add ¼ cup wine and a good pinch of salt. Add chicken thighs back on top of leeks, skin side up, and place in oven for about 10 minutes or until cooked through.
OPTIONAL: For crispy top, heat oil in a small frying pan and add leek tops. Cook until golden brown - about 3 minutes. Remove and drain on paper towel, sprinkle with salt.
Once chicken is cooked, remove from pan along with leeks. Chop leeks into ½ inch slices and return to pan over medium-high heat.
Add ⅓ cup cream and bring to a simmer. Add ¼ cup parmesan and a splash of lemon juice, then remove from heat.
Serve chicken back into pan or onto plates with sauce drizzled over, topped with crispy leek bits.
