Insane Mushroom Burger - Sutter Home Family Vineyards

Ingredients

• 1/4 pound unsalted butter, soft
• 1 tablespoon white truffle oil
• 2 pounds ground chuck
• 1 cup porcini mushrooms, minced (if using frozen, thaw and drain first)
• 1/2 cup grated Parmesan cheese
• 4 cloves garlic, minced
• 1 teaspoon kosher salt
• 1 teaspoon ground black pepper
• 3 cups baby spinach, pre-washed in a bag
• 1 cup Gorgonzola cheese, crumbled
• 6 Kaiser rolls, split