Meanwhile, cook sausage in a large heavy frying
pan over medium heat until edges begin to curl and fat renders, about 4 minutes. With a slotted spoon, transfer sausage to bowl of bread cubes, leaving fat behind (if there isn’t any fat, add 2 tbsp. oil). Increase heat to medium-high, add shiitakes, and cook until golden, about 5 minutes. Season lightly with salt and pepper, then scoop into bowl of sausage and bread cubes.