Potato and Leek Gratin

Ingredients

• 2 Tbsp unsalted butter, plus more for the pan
• 2-2 ½ pounds gold potatoes, unpeeled, scrubbed and thinly sliced
• 1-2 medium to large leeks, halved, washed, cut into 1-inch segments
• 2 cups heavy cream
• Kosher salt
• freshly ground black pepper
• 2 garlic cloves, minced
• Leaves from 3 sprigs fresh thyme
• ½ cup plain breadcrumbs
• ¾ cup coarsely grated Gruyere, Comte, or cheddar cheese