Preheat oven to 375°F. Spray or grease a 13X9 baking dish.
In a skillet over med/high heat, crumble and brown sausage roll. Drain grease. Set crumbled sausage aside.
In a mixing bowl, whisk together flour, baking powder and salt. Set aside.
In a large (separate) mixing bowl, whisk together eggs, milk and melted butter.
Add flour mixture into liquid mixture. Whisk until thoroughly combined.
Stir in sausage, 1 cup of shredded cheese, minced onion and a pinch of salt & pepper.
Pour into greased 13X9 baking dish and bake until toothpick inserted in center comes out clean - about 30 - 35 minutes.
Sprinkle remaining 1 cup of shredded cheese over top of casserole. Bake for an additional 3-5 minutes or until cheese is melted.
Let casserole rest for 5-10 minutes before serving. Cut into squares and top with sour cream or snipped chives if desired. Enjoy :)