Ingredients
Method
1. Prep the Oven & Dish
Set your oven to 375°F (190°C). Lightly coat a 9×13-inch glass baking dish with butter or spray to prevent sticking.
2. Slowly Cook the Onions
Melt butter in a large skillet over medium heat. Add onions with a pinch of salt. Cook gently, stirring now and then, until they turn soft and golden—about 20–25 minutes. Sprinkle sugar if you want to speed things up. Let cool slightly.
3. Build the Cream Mixture
In a large bowl or measuring jug, combine cream, Parmesan, remaining salt, pepper, and thyme. Stir in the warm onions until everything blends into one rich mixture.
4. Slice the Potatoes
Cut potatoes into thin rounds (about ⅛ inch thick). Keep slices even so they cook perfectly—no undercooked centers.
5. Layer the Dish
Spread potato slices evenly in the prepared dish. Don’t stress about perfection—just avoid thick clumps.
6. Pour & Settle
Pour the creamy onion mixture evenly over the potatoes. Gently shake the dish or press lightly so the liquid seeps through all layers.
7. Add Topping & Cover
Sprinkle extra Parmesan on top. Cover tightly with foil to lock in moisture.
8. Bake Until Tender
Bake covered for 45–55 minutes, until potatoes are soft when pierced.
9. Finish Uncovered
Remove foil and bake another 15–20 minutes until the top turns golden and bubbly.
10. Rest Before Serving
Let sit for 10 minutes before serving so the sauce thickens. This step makes a BIG difference—don’t skip it.

