Black Forest Ham and Cheese Breakfast Casserole

INGREDIENTS

8 oz

Forest deli ham, black

Eggs, large

1/4 cup

Mustard, whole-grain

1/4 tsp

Black pepper, freshly ground

1 tsp

Kosher salt

4 cups

Pumpernickel bread, day-old or toasted

2 cups

Sourdough bread, day-old or toasted

2 cups

Gruyere cheese, grated

2 1/2 cups

Whole milk