Rinse the breast and pat dry. Trim off any excess fat.
Melt the butter in a small saucepan over medium heat. Stir in the seasoning
Fill an injector with half of the butter mixture (working in batches if necessary) and inject throughout the turkey. Get the needle deep into the meat of the thighs and breast.
Blot the turkey breast dry.
Place the turkey breast on a rimmed baking sheet and let sit out at room temperature for 1 hour.
Place the breast over the aluminum pan. Close the lid and cook for 1 to 1 1/2 hours, basting with the remaining butter mixture every 20 minutes.
After 1 1/2 hours, and once the breast has started to turn golden brown, keep cooking and basting until the internal temperature reaches 165 F. Make sure to measure the temperature in several locations, and do not let the thermometer touch the bone when testing.
Remove turkey and let rest for 15-20 minutes before slicing. and serving.
Notes
Use a BBQ seasoning that will dissolve easily in the butter. You don't want big chunks of 'stuff' that might clog the injection needle. If you have to, strain the butter mixture before injecting.