Stacie's Surprise Burger - Sutter Home Family Vineyards

Ingredients

• 4 Large yellow onions
• 1 stick unsalted butter
• 2 tablespoons extra virgin olive oil
• 1 teaspoon salt
• 1 teaspoon cracked black pepper
• 1 pound ground chuck
• 1 pound ground sirloin
• 1 package onion soup mix
• 2 teaspoons cracked black pepper
• 6 slices Gruyeres cheese
• 1 small package fresh Arugula leaves
• 1 cup mayonnaise
• 10-15 fresh basil leaves-depending on size