Add the butter, garlic, herbs, salt, and pepper to a microwave-safe bowl. Heat on high for 1 to 2 minutes until melted, then stir well. Let it sit for 5 minutes so the flavors infuse, then microwave 30 seconds more.
Pour the warm butter through a fine sieve into a clean bowl. This gives you a smooth liquid that won't clog the needle. Save the garlic and herbs in the sieve, because you'll rub them on the turkey later.
Heat your oven to 450°F. Place the turkey breast side up in the roasting pan. Cover it loosely with plastic wrap so the butter doesn't splatter everywhere.
Fill the injector with the strained butter. Inject the breast all over in a diamond pattern, using a small amount at each spot. Push the leftover butter into the thighs and drumsticks.
Spread the saved garlic and herb mixture over the skin and inside the cavity. Add any butter that pooled in the pan. For extra flavor, gently slide some of it under the skin.
Remove the plastic wrap. Sprinkle 1 teaspoon of kosher salt evenly over the bird. Pat it down lightly so it sticks.
Insert your probe thermometer into the thickest part of the breast, away from the bone. A probe lets you watch the temperature without opening the oven. This takes the guesswork out of roasting.
Roast at 450°F for 10 to 15 minutes until the skin starts to brown. Brush gently with the melted butter. This quick blast kickstarts a crisp, golden crust.
Reduce the oven to 325°F and roast for about 2 hours 30 minutes. Brush with pan juices about 1 hour in, then again 45 minutes later. Pull it when the breast hits 160°F.
Let the turkey rest at least 5 minutes before carving. The temperature will rise to a safe 165°F as it rests. Slice and serve while the meat is hot and juicy.