How to Make It
Preheat oven to 425° .
On a rimmed baking sheet, toss mushrooms, sweet potatoes, fennel, and apples with 3 tablespoons oil; sprinkle with 1 teaspoon salt and ½ teaspoon pepper. The sheet pan will be crowded, but roasting will shrink their size.
Dry chicken thoroughly with paper towels. Rub top with remaining 3 tablespoons extra-virgin olive oil. Sprinkle inside and outside of chicken evenly with remaining 2 teaspoons salt and ½ teaspoon pepper.
Stuff chicken cavity with lemon slices, thyme sprigs, rosemary sprigs, and garlic cloves.
Place chicken, breast side up, on top of the vegetable mixture on the sheet pan.
Roast at 425° for 25 minutes. Reduce oven temperature to 325°; continue roasting, rotating pan occasionally, until a meat thermometer inserted in thickest part of thigh registers 165°F to 170°F, another 90-95 minutes. Let stand 15 minutes before carving.