Potato-Fennel Gratin - Food Gardening Network

Ingredients

• 2 fennel bulbs, fronds (the leafy top) removed, and cut into slices
• 1 yellow onion, peeled, halved, and thinly sliced crosswise
• 2 tablespoons extra-virgin olive oil
• 1 tablespoon unsalted butter
• 2 pounds Russet potatoes, peeled and thinly sliced (try using a mandoline slicer for the most consistent thinness)
• 2 cups, plus 2 tablespoons, heavy whipping cream, divided
• 2 1/2 cups grated Gruyère cheese, divided
• 1 teaspoon Kosher salt
• 1 teaspoon freshly ground black pepper