French Onion Grilled Cheese Sandwich

Ingredients

• 1 lb yellow onions (about two large onions, peeled and sliced thinly)
• 1 tbsp olive oil
• 1 tbsp unsalted butter
• ½ tsp granulated sugar
• ¼ tsp sea salt
• 2 garlic cloves (minced)
• 3 tbsp dry red wine (Malbec recommended)
• a pinch of cinnamon
• black pepper to taste
• 4 slices sourdough bread (large and fresh)
• 4 tbsp unsalted butter (melted)
• ⅛ tsp dried thyme
• ⅛ tsp dried rosemary
• 7 oz shredded white cheddar (or 4 slices)
• 3 oz shredded Gruyère cheese