Egg Mushroom Kielbasa Bake

Bahan-bahan (8 porsi)

• 3 tablespoons salted butter, (softened)
• 12 slices white bread
• ½ cup (1 stick) butter, (softened)
• 8 ounces sliced fresh mushrooms
• 2 cups thinly sliced sweet onions
• 1½ pounds Kielbasa sausage, (sliced into bite-sized pieces)
• 1 pound grated cheddar cheese ((Mexican shredded blend is good for this, too))
• 5 large eggs
• 2½ cups milk
• 1 tablespoon Dijon mustard
• 1 teaspoon dry mustard
• 1 teaspoon ground nutmeg
• salt and pepper, (to taste)
• 2 tablespoons finely chopped fresh parsley