Pat the chicken thighs dry with paper towels then season generously on both sides with salt and pepper.
Place the chicken, skin-side down, into a large pan. Place over medium-high heat and allow the fat to render slowly and for the skin to brown (for approximately 7-10 minutes).
Turn the thighs over and cook for another 10 minutes on the other side. The chicken should be almost completely cooked by now. When cooked, chicken will read 73ºC/165ºF. If your chicken is not cooked through yet, cook for a few minutes longer on each side or pop into a hot oven for 5 minutes.
Once cooked, remove the chicken from the pan and set aside.
In the same pan, add the crushed garlic, chilli flakes and oregano. Cook for 30 seconds until fragrant then add the beans and spinach.
Cook until the spinach has wilted then pour in the chicken stock. Allow to come to a simmer and cook for 5 minutes then add the butter and lemon juice and stir in.
Top with the chicken and allow to cook for another 5 minutes. Season to taste and serve with lemon slices.