Ingredients:

• Cooking spray
• 6 ounces aged extra-sharp cheddar cheese (such as Old Croc), grated (about 1 1/2 cups)
• 2 ounces cheddar cheese, grated (about 1/2 cup)
• 2 pounds russet potatoes, peeled and sliced crosswise into 1/4-inch-thick rounds (about 5 cups)
• 1 1/4 cups heavy whipping cream
• 1 cup whole milk
• 1 teaspoon kosher salt
• 1/2 teaspoon black pepper
• 2 medium garlic cloves, smashed
• 2 (3-inch) thyme sprigs
• 2 tablespoons chopped fresh chives, plus chives for garnish

Cooking Instructions:

1. Preheat oven to 425°F. Spray an 8-inch square baking dish with cooking spray.
2. Combine cheeses in a medium bowl. Set aside.
3. Bring potatoes, cream, milk, salt, pepper, garlic, and thyme to a simmer in a large saucepan over medium-high. Reduce heat to medium-low; cover and cook, stirring occasionally, until potatoes are mostly tender, about 8 minutes. Remove from heat, and gently stir in chives and 1 1/2 cups cheese mixture. Discard thyme sprigs.
4. Transfer potato mixture to prepared baking dish, spreading into a relatively even layer; sprinkle with remaining 1/2 cup cheese mixture. Bake in preheated oven until bubbling around edges and top is golden brown, 20 to 25 minutes. Remove from oven, and let cool at room temperature for 15 minutes. Cut additional chives into 1-inch pieces, and garnish.