Lightly butter both side of bread slices and place in 9x13-inch baking dish.
In nonstick skillet, over medium-high heat, brown beef sausage; drain well and pat with paper towels. Sprinkle sausage over bread slices.
Sprinkle cheese over sausage. Follow with a layer of chopped green chilis.
In medium bowl, beat eggs lightly. Add salt, dry mustard and half-and-half. Mix thoroughly. Pour over casserole.
Cover with foil and refrigerate overnight.
To bake, preheat oven to 350°F and bake casserole 45 minutes, or until bubbly and lightly browned. Allow to stand 15 minutes to set. Cut into squares and serve with picante sauce on the side.
