Whisk together half the oil, half the lemon juice, the crushed garlic, thyme and plenty of salt and pepper. Add the chicken and mix well and leave to marinate overnight.
Heat the oven to 220°C/430°F. Mix the potatoes and shallot halves with the rest of the oil and plenty of salt and pepper. Spread on one half of a large baking tray. Put the chicken thighs on the other half of the tray and put in the oven.
Cook for about 40 minutes until the chicken is cooked through and the potatoes are crispy. If the potatoes need longer then take the chicken out and return the potatoes to the oven for a bit longer. To get everything super crispy switch the oven to grill for the final 5 minutes.
Place everything on a serving platter sprinkle over the feta, dill and lemon slices.
Nutrition information is an estimate and will vary depending on the exact ingredients used.