Potato and Spinach Gratin

Potatoes

1. Position oven racks in the upper and lower thirds of the oven. Preheat to 200°C (180°C fan-forced).
2. Toss the potato slices with 3 tbsp olive oil in a large bowl until well coated. Divide between 2 large baking trays and spread in an even layer.
3. Roast for 20-25 minutes, rotating the trays from top to bottom halfway through, until the potatoes are tender and beginning to brown.

Spinach Sauce

1. Meanwhile, heat 2 tbsp olive oil in a large saucepan over medium heat.
2. Add the onion and cook for 5-8 minutes, stirring frequently, until very soft and golden brown.
3. Add the garlic and cook for 1 minute until fragrant.
4. Add the flour, salt, and pepper. Stir for 1 minute until combined, scraping up any brown bits from the bottom of the pan.
5. Gradually add the a2 Milk® Full Cream, stirring constantly. Increase heat to medium-high and cook for 3-5 minutes, stirring, until the sauce thickens and bubbles.
6. Remove from heat. Squeeze any excess moisture from the spinach and stir into the sauce.

Assembly

1. Remove potatoes from oven. Preheat the grill to high.
2. Transfer half the potatoes to a 25cm x 35cm baking dish. Spread half the sauce over the potatoes and sprinkle with 1/2 cup Manchego.
3. Add the remaining potatoes, then top with the remaining sauce and 1/2 cup Manchego.
4. Grill for 3-5 minutes, watching carefully, until the sauce is bubbling and the cheese is golden brown.
5. Rest for 10 minutes before serving.