Ham, Swiss, and Tomato Strata

INGREDIENTS

• Unsalted butter, for greasing dish
• 1 pound Italian loaf, crust removed, cut crosswise into 1/2-inch slices
• 1 cup diced Virginia ham (1/4-inch dice)
• 2 cups grated Swiss cheese
• 2 tablespoons minced chives
• 3 small tomatoes, cored and sliced into 1/4-inch rounds
• 8 large eggs
• 4 cups milk
• 2 tablespoons Dijon mustard
• 2 teaspoons coarse salt
• 1/4 teaspoon freshly ground black pepper