Strata with Sausage and Greens

INGREDIENTS

• Salt
• 3/4 cups grated Gruyere
• 1/4 teaspoon freshly ground nutmeg
• 1 cup finely chopped shallots
• 1/4 cup heavy cream
• 1 pound sweet Italian sausages
• 1/2 cup grated Parmesan
• 1 large bunch kale, spinach, or chard, stems removed, washed, dried and roughly chopped (about 6 cups)
• 6 large eggs
• 1/2 cup grated Pecorino
• 1 tablespoon Dijon mustard
• 1 1/2 cup whole milk
• 6 1/2 cups cubed stale bread (3/4-inch)
• 1 tablespoon olive oil
• Unsalted better (for the baking dish)
• 1/8 teaspoon freshly ground black pepper