Preheat the oven to 375°F (190°C). Place an oven rack in the center position.

In a microwave‑safe bowl, microwave 1/2 cup (1 stick) unsalted butter until melted, about 30–60 seconds. (If you prefer, melt the butter on the stovetop in a small saucepan over low heat.)

Stir the melted butter together with 4 cloves minced garlic, 2 Tbsp Italian seasoning, 1 tsp sea salt, and 1/2 tsp black pepper until evenly combined to make the garlic butter sauce.

Remove the 4 to 5 pounds of bone‑in, skin‑on chicken thighs from their packaging and pat them dry with paper towels. Dry skin helps achieve crispiness.

Arrange the chicken thighs in a single layer in a large casserole dish or baking dish, skin side up. Do not overlap the thighs.

Spoon and spread the garlic butter sauce evenly over the skin of each thigh so the full surface of the skin is coated.

Bake on the center rack at 375°F for 40 minutes.

Carefully remove the dish from the oven and use a spoon to baste the thighs with the pan juices.

Increase the oven temperature to 425°F (220°C). Return the dish to the oven and bake an additional 5–10 minutes, until the skin is golden brown and reaches your desired level of crispness.

For extra crispiness, move the oven rack to the shelf that is third from the top (if it is not already there) and broil on high for 3–5 minutes, watching closely to prevent burning.

Check doneness by inserting a meat thermometer into the thickest part of a thigh without touching the bone. The chicken is safe at 165°F, but bone‑in thighs often taste and feel better when cooked to about 180°F; cook to your preferred doneness (not below 165°F).

Let the thighs rest 3–5 minutes before serving. Spoon any pan juices over the chicken when serving.