Ground Beef and Twice-Baked Potato Pie

1  lb lean (at least 80%) ground beef
1/4  cup chopped onion
1/4  cup Progresso® plain bread crumbs
1/2  teaspoon dried sage leaves
1/2  teaspoon salt
1  egg
1  package (1 lb 8 oz) refrigerated garlic mashed potatoes
1  cup shredded Cheddar cheese (4 oz)
1/4  cup chopped fresh tomato, if desired
2  slices precooked bacon, chopped, if desired
2  medium green onions, chopped (2 tablespoons), if desired

Heat oven to 350°F. In large bowl, mix beef, onion, bread crumbs, sage, salt and egg until well blended. Press in bottom of ungreased 8-inch square (2-quart) glass baking dish. Spread mashed potatoes evenly over top. Sprinkle evenly with cheese.
Bake uncovered about 50 minutes or until meat thermometer inserted in center of beef mixture reads 160°F. Sprinkle with tomato, bacon and green onions. 
Serves 4.