Preheat oven to 400°F (200°C)

Slice the top off the garlic bulb, drizzle with olive oil, season with salt & pepper, wrap in foil, and roast for about 60 minutes until soft and caramelized. Once cooled, squeeze the roasted garlic out of the cloves and mash it with a fork. Set aside.

Wash and peel the potatoes. Slice them thinly (about ⅛-inch thick). Place the sliced potatoes in a bowl of cold water to prevent browning.

In a saucepan on medium low heat half & half with fresh thyme, rosemary, bay leaves, Parmesan rind, and salt. Allow to simmer for 10-15 minutes. Strain and set aside.

In a saucepan on medium heat add olive oil, butter, and onions. Cook until translucent about 4-5 minutes.

Add flour and whisk until flour is cooked.

Pour in the half and half, stirring to combine. Simmer for 4 minutes stirring frequently until thickened.

Add garlic powder, onion powder, dried thyme, paprika, and toasted garlic. Mix until combined.

Stir in the cheeses until melted and smooth. Season with salt and pepper to taste.

Grease a 9x13-inch baking dish with butter or cooking spray. Layer the sliced potatoes evenly in the dish, slightly overlapping. Pour the creamy sauce over the potatoes and spread to make sure it is evenly coated.

Cover the dish tightly with aluminum foil and bake at 325°F (165°C) for 90 minutes, or until the potatoes are tender when pierced with a fork.

Remove the foil and bake uncovered on broil for 3-5 minutes or until top is golden and bubbly.