Heat oven to 425ºF. Spray bottom and sides of 13x9-inch (3-quart) glass baking dish with cooking spray or grease with shortening. In 12-inch skillet, cook sausage, apples and onion over medium-high heat 8 to 10 minutes, stirring frequently, until sausage is no longer pink; drain if necessary. Spoon into baking dish.
In medium bowl, beat eggs and 1/2 teaspoon salt with wire whisk or fork until well mixed. Pour eggs over sausage mixture.
In large bowl, mix flour, baking powder, sugar, baking soda and 1 teaspoon salt. Cut in butter, using pastry blender (or pulling 2 table knives through ingredients in opposite directions), until mixture looks like coarse crumbs. Stir in cheese and green onions. Add buttermilk; stir just until combined. Drop dough by rounded tablespoonfuls evenly onto sausage mixture.
Bake uncovered 20 to 30 minutes or until biscuits are deep golden brown and done in the middle. Let stand 10 minutes before serving.