Place halved new potatoes and halved yellow pepper filled with scored cherry tomatoes on a lightly oiled oven tray, season with salt and pepper, drizzle with olive oil, add small knobs of butter and 2 sprigs of rosemary to potatoes, and roast in oven at medium heat for 10 min.
Meanwhile prepare chicken thigh - season with salt and pepper, slip a thin slice of butter under the skin, and place small knobs of butter and 3 smashed garlic cloves on other side.
When vegetables are soft, place chicken skin-side down on bed of pepper and tomatoes and roast on high heat for 10 min. Finally, flip chicken skin-side up and grill for 10 min.
Once chicken is done, plate up and drizzle any juice from the tray onto the chicken and potatoes. Serve!