Potato and Butternut Squash Gratin with Crispy Shallots

Ingredients

• 3 shallots, peeled
• 2 cups neutral oil such as canola
• Kosher salt
• 1 ½ pounds butternut squash, neck only, ideally less than 3” diameter
• 1 ½ pounds large waxy potatoes, such as red, about 3 medium potatoes
• 16 oz (2 cups) whole milk
• 16 oz (2 cups) heavy cream
• 4 large garlic cloves, smashed
• 2 sprigs thyme
• 2 bay leaves
• 4 ounces gruyere cheese, finely grated
• 1 tablespoon kosher salt
• A few cracks of freshly ground black pepper
• Butter, for greasing