Preheat oven to 350°F. Line a baking sheet with foil or parchment paper.
Cut a long well down the middle of the bread. You want a good ¾-inch or more of bread left on all sides after cutting out the well. Place bread on baking sheet.
Sprinkle ham and spinach evenly into the well.l
In a large bowl, whisk together eggs, milk, salt, pepper, and mustard until combined. Pour carefully into the well over the ham and spinach. If you have leftovers, discard. You don’t want the eggs to overflow.
Sprinkle cheese evenly over the top of the egg mixture and bread.
Bake for 35 to 40 minutes ,or until eggs are no longer runny in the center of the boat.
Slice and enjoy immediately.
Notes
If you’re not a mustard lover, omit or decrease amount to ½ teaspoon.
Nutrition information is a little misleading because a fair amount of the bread is removed.