Adjust rack to middle position and preheat oven to 425 degrees. Wash and dry produce.

Trim, peel, and cut carrots on a diagonal into 1-inch-thick pieces. Halve, peel, and cut onion into 1-inch pieces. Peel and halve garlic. Trim green beans if necessary.

Pat chicken* dry with paper towels and season all over with salt and pepper. TIP: See a feather? Simply grip the end using a paper towel and pull! 

Place chicken, skin side up, on top of veggies. Pour seasoned butter on chicken and rub all over to evenly coat. TIP: Don’t forget to season the underside of the chicken!

Roast chicken and veggies until chicken is browned and cooked through and carrots are tender, 40-50 minutes. TIP: If skin begins to brown too quickly, loosely cover top of chicken with foil. To ensure chicken is cooked through, insert a thermometer into the innermost part of the thigh and breast (avoiding any bones). Once chicken is cooked, the bones may still appear pink—this is OK!

While chicken and veggies roast, dice potatoes into ½-inch pieces. Place potatoes in a medium pot (large pot for 4 servings) with enough salted water to cover by 2 inches. Bring to a boil and cook until tender, 15-20 minutes. 

Reserve 1 cup potato cooking liquid (2 cups for 4), then drain and return potatoes to pot. Add garlic herb butter and ¼ cup reserved potato cooking liquid (½ cup for 4). Mash with a potato masher or fork, adding additional splashes of reserved potato cooking liquid if needed, until smooth. Season with salt and pepper. Keep covered off heat until ready to serve.

While potatoes cook, melt 1 TBSP plain butter (2 TBSP for 4 servings) in a medium pan over medium heat.

Sprinkle flour over melted butter and cook, stirring constantly, until lightly browned, 1-2 minutes.

Slowly whisk in remaining reserved potato liquid. Add onion paste and stock concentrates. Cook, whisking constantly, until gravy has thickened, 3-5 minutes.

Remove from heat. Stir in sour cream. Taste and season with salt and pepper if desired. Keep covered off heat until ready to serve.

When chicken and veggies are done roasting, place green beans in a medium microwave-safe bowl; cover with plastic wrap and poke a few holes in wrap. Microwave until tender, 3-4 minutes, tossing halfway through. 

Carefully uncover (watch out for steam!); season with salt and pepper. TIP: When ready to serve, mashed potatoes and gravy can be reheated in the microwave if necessary.

Transfer roasted chicken and veggies to a serving platter. Serve family style with garlic-herb mashed potatoes, green beans, and gravy on the side. TIP: Carve the chicken using your sharpest knife (use a carving knife if you have one!). First, cut the skin near the thigh to expose the joint. Cut through the joint, removing the leg from the carcass. Cut the joint between the thigh and drumstick, separating the two. (Use the heel of your blade—near the handle—for the most force and stability.) Cut off the wing. Then, starting at the neck end, cut along the breastbone. Angle your knife and cut against the rib cage to remove the breast. Slice breast meat crosswise. If desired, remove the thigh bone and slice the meat.