In a large skillet melt butter over medium-high heat. Add mushrooms; cook about 5 minutes or just until tender, stirring occasionally. Add green onions for the last 1 minute of cooking. Remove from heat. Stir in soy sauce, rosemary, and pepper.
In a very large bowl combine mushroom mixture, herb-seasoned stuffing croutons, and carrots. Drizzle with enough of the 1 1/4 to 1 1/2 cups water to moisten; toss lightly to combine. Spoon into a 2 1/2-quart casserole. (To serve today, omit Step 3 and continue as directed in Step 4, except bake, covered, for 50 to 60 minutes or until hot in center [165 degrees F].)
Cover with plastic wrap; chill for up to 24 hours.
Preheat oven to 325 degrees F. If chilled, remove plastic wrap. If desired, drizzle with an additional 1/4 cup water to moisten. Bake, covered, for 60 to 70 minutes or until hot in center (165 degrees F). (For safety reasons, do not make stuffing ahead if planning to use for stuffing a turkey.)