Golden Russet Potato Gratin

By charlotteh371

Ingredients

• 1-1/2 Tbs. olive oil
• 2 large yellow onions (about 1 lb. total), halved and thinly sliced from root to blossom end
• Kosher salt
• 1-1/2 cups low-salt canned chicken broth
• 3 Tbs. unsalted butter
• 3-1/2 lb. russet potatoes (about 6 medium)
• 2 tsp. fresh thyme leaves
• Freshly ground black pepper
• 1 cup lightly packed grated Gruyère (about-1-1/2 oz.)
• 3 Tbs. freshly grated Parmigiano Reggiano

Preparation

Step 1

Heat the oven to 400°F. Heat a large skillet over medium heat, add the oil, and when it’s-hot, add the onions. Season well with salt and cook, stirring often, until the onions turn translucent and soften completely, about 10 min. Raise the heat to high and cook, stirring constantly, until the onions darken uniformly to a light brown, about 4 min. Carefully add the chicken broth (it will steam) and scrape the bottom of the pan to incorporate the browned bits into the broth. Remove from the heat.