Peter Som's Big Easy Mushroom Strata - Rombauer Vineyards

Ingredients

• 2 tablespoons unsalted butter, as well as more for the pan
• 1(1-pound) boule sourdough bread, cut into 1-inch cubes (about 8 cups)
• 1 large shallot, diced
• 2 garlic cloves, minced
• 1 pound mushrooms, sliced
• 2 tablespoons thyme leaves, minced
• Kosher salt
• Freshly ground black pepper
• 3 ounces baby spinach
• I cup frozen peas
• 2 teaspoons oyster sauce
• 1 ¼ cups grated Gruyère (about 5 ounces), divided
• 1 1/2 cups grated mozzarella (about 6 ounces)
• 8 large eggs
• 2 cups whole milk
• 8 ounces cream cheese, at room temperature
• 2 tablespoons white or yellow miso
• 1 tablespoon Dijon mustard
• ¼ teaspoon ground nutmeg
• ½ teaspoon ground allspice