Preheat the oven: preheat the oven to 180°C / 350-375°F / Gas Mark 4-5. (Note: this step needs to be done about 10 minutes before you want to place the chicken into the oven).
Lemon zest: use a chopping board and microplane zester to zest the 2 lemons and add this to a small bowl.
Marinade: add the olive oil, lemon juice, lemon zest, garlic powder, onion powder, dried parsley, dried oregano, dried basil, salt and pepper to a large bowl and use a whisk to combine.
Chicken thighs: remove the chicken thighs from the packaging and add them to the bowl with the marinade. Use kitchen tongs to toss and combine. Then cover the bowl with cling wrap and place it into the refrigerator for a minimum of 15 minutes up to 24 hours.
Oven bake: remove the marinated chicken thighs from the fridge and discard the cling wrap. Then spray a baking dish with olive oil. Pour the chicken thighs and marinade into the baking dish and then cover it with aluminium foil. Place the baking dish onto the middle shelf of a preheated oven and bake the chicken for 30 minutes.
Grill/broil: use oven mits to remove the baking dish from the oven and place it onto a heatproof surface. Change the oven setting to grill at 200°C 392°F6. Use kitchen tongs to transfer each chicken thigh to a silicon baking mat on an oven rack and tray. Use the pastry brush to coat each thigh with the reserved marinade. Then place the tray into the oven on the top shelf. Grill the chicken thighs for 10 mins. Then remove, repeat the basting process followed by a further 10 mins grill time (Grill time total: 20 minutes).
Serve: use oven mits to remove the baking tray from the oven and place it onto a heat proof surface. Let the chicken thighs rest for 2 to 3 minutes before using tongs to transfer them to a serving plate. Garnish with flat leaf parsley, lemon wedges and provide Horseradish Yogurt Sauce (optional).