If using chicken breasts, pat dry, and, on a separate cutting board, cut into 1” pieces. Follow same instructions as diced chicken.
If using shrimp, follow same instructions as diced chicken in Steps 1 and 2 cooking undisturbed until seared on one side, 2-3 minutes. Flip, and cook until shrimp reaches minimum internal temperature, 1-2 minutes. Add shrimp to chowder right before plating.
If using Italian sausage, on a separate cutting board, remove sausage from casing. Follow same instructions as diced chicken in Steps 1 and 2, breaking up meat until no pink remains and sausage reaches a minimum internal temperature of 160 degrees, 4-6 minutes.