Preheat oven to 425°F. Line a baking sheet with parchment paper and set aside.
In a small dish, combine the thyme, salt, onion powder, paprika, pepper, garlic, lemon zest, and butter.
1 tablespoon chopped fresh thyme, 1 teaspoon kosher salt, ½ teaspoon onion powder, ½ teaspoon ground paprika, ½ teaspoon ground black pepper, 3 cloves garlic, ½ lemon, 4 tablespoons unsalted butter
Place the chicken, breast side down, onto the prepared baking sheet..
1 (4-pound) whole chicken
Pat the chicken dry with paper towels.
Locate the backbone of the chicken. Using a pair of kitchen shears, cut through the ribs along both sides of the backbone. Remove the backbone.
Once the backbone is removed, spread the rib cavity apart. The chest bone runs down the middle of the rib cavity. Use your knife to score down the breast bone.
Flip the chicken over and push firmly on the center of the chicken where the breast bone is, so the chicken lays flat.
Spread half of the the butter herb mixture all over the chicken and underneath the skin by the breasts and thighs. Then, flip it over and spread the rest on the exterior and inside the rib cavity.
Flip the chicken over again so it lays flat on the sheet pan.
Roast for 40-45 minutes, or until the internal temperature at the thickest part of the breast reaches 160-165°F.
Let the chicken rest for 5-10 minutes before slicing.