If using whole chicken breasts, pat dry and, on a separate cutting board, cut into 1" dice. Follow same instructions as diced chicken in Steps 2 and 4.
If using shrimp, pat dry and season all over with a pinch of salt and pepper. Follow same instructions as diced chicken in Step 4, cooking undisturbed until seared on one side, 2-3 minutes. Flip, and cook until shrimp reaches minimum internal temperature, 1-2 minutes.