Preheat the oven to 190°C / 375°F.

Step 1 - Roast The Garlic

• In a large casserole dish, add the garlic heads drizzled with the oil.
  3 whole garlic heads, Extra Virgin Olive Oil
• Cover with foil and roast for 40 minutes, until tender. Leave to cool for around 30 minutes, then squeeze out the cloves.

Step 2 - Prepare The Garlic And Cream Sauce

• Mash the garlic to a paste and transfer to a saucepan. Add the double cream, thyme and rosemary and bring to a light boil, then immediately reduce the heat.
  500 ml double cream, 1 tsp dried thyme, 1 tsp dried rosemary, 1 tsp garlic powder
• Simmer over very low heat until reduced slightly, this will take around 5-10 minutes; season with salt and pepper.
  Salt and freshly ground pepper

Step 3 - Arrange Layers

• Arrange a layer of the potatoes in the bottom of a 12 x 8 inch baking dish. Top with shredded cheeses and drizzle lightly with the garlic cream.
  500 g 17oz. potatoes, peeled and thinly scalloped, 2 cups loosely packed Spanish Manchego cheese, grated, 1 cup loosely packed smoked Gouda cheese, grated
• Repeat the layering with the remaining potatoes, cheese and cream. Pour any remaining cream on top.

Step 4 - Bake

• Bake the gratin on the middle shelf for 1 hour, until golden and bubbling. Then remove from the oven to cool.
• Leave to cool for at least 20 minutes before serving.