In a large bowl, whisk the eggs, milk, mustard and salt. Stir in the sausage, bread cubes and cheese. Pour into a greased 13x9-in. baking dish. Immediately bake per instructions in step 2 or cover and refrigerate overnight.
If refrigerated, remove 30 minutes before baking. Bake, uncovered, at 350° for 30-40 minutes or until a knife inserted in the center comes out clean. Let stand for 10 minutes before serving.
Recipe by Sweet Hope Lifestlye at https://sweethopestudio.com/sausage-breakfast-casserole/