Cut sausage into 1/2-inch-thick slices; cut slices into quarters. Cut stems from mushrooms and, if desired, reserve for another use; cut mushroom caps into slices.
Melt 1 tablespoon butter in a nonstick skillet over medium-high heat; add sausage, and sauté 7 minutes or until lightly browned. Remove sausage from skillet. Add mushroom caps to skillet, and sauté 5 minutes or until tender.
Bring 3 cups water to a boil in a Dutch oven. Gradually stir in grits; return to a boil. Reduce heat, and simmer, stirring occasionally, 5 minutes or until thickened. Add remaining 7 tablespoons butter and cheese; cook, stirring often, 5 minutes or until melted and blended. Remove from heat; stir in eggs, rosemary, and seasoned salt until blended. Stir in sausage and mushrooms; pour mixture into a lightly greased 11- x 7-inch baking dish.
Bake at 350° for 45 to 50 minutes or just until set. Sprinkle top with olives, if desired.
Note: For testing purposes only, we used Gerhard's Smoked Chicken Sausage with Apples & Chardonnay.