1-Step 1: Preheat and prep the potatoes Preheat the oven to 350 degrees F. Peel the Yukon Gold potatoes and slice them into 1/8 inch thick rounds. Try to keep the slices even so they cook at the same pace. This is one of the most important parts of making Easy Au Gratin Potatoes because thin, uniform slices bake more smoothly.

2-Step 2: Start the flavor base Melt the butter in a saucepan over medium heat. Add the chopped yellow onion and cook it until softened. Stir in the minced garlic for about 30 seconds. You want the garlic fragrant, not browned, so it stays sweet and mellow in the sauce.

3-Step 3: Make the roux Whisk in the flour to form a roux. Cook it briefly while stirring so the raw flour taste cooks out. This gives the sauce body and helps the final dish hold together well. If you need a gluten-free version, this is the step where you would use a gluten-free flour blend or another thickener.

4-Step 4: Add milk and cream slowly Gradually pour in the whole milk and heavy cream while whisking constantly to prevent lumps. Keep whisking until the mixture becomes smooth. Bring it to a simmer and cook until the sauce thickens. This creamy base is what makes Creamy Au Gratin Potatoes so satisfying.

5-Step 5: Add cheese and seasonings Stir in the shredded cheddar cheese and half of the Parmesan cheese. Add the salt and pepper, then stir until the cheese melts completely. The sauce should taste savory and rich at this point. If you want a stronger cheese flavor, you can use part Gruyère instead of some of the cheddar, which is a nice flavor twist for Au Gratin Potatoes.

6-Step 6: Fold in the potato slices Gently fold the sliced potatoes into the sauce until every piece is coated. Take your time here so the slices do not break. The sauce should cling to the potatoes without pooling too much at the bottom. If the sauce seems thin, let it simmer a little longer before adding the potatoes.

7-Step 7: Assemble the baking dish Transfer the mixture to a greased 2-quart baking dish. Spread it evenly so the top bakes at the same rate. Sprinkle the remaining Parmesan over the top for a savory crust. This final layer gives the dish that classic golden finish people expect from Au Gratin Potatoes Recipe results.

8-Step 8: Bake until tender Cover the dish with foil and bake for 1 hour, or until the potatoes are tender. Then remove the foil and bake for 20 more minutes so the top turns golden and lightly crisp. If you are making this ahead, remember that chilled potatoes may need a little extra time in the oven.

9-Step 9: Rest and serve Let the dish rest for 5 minutes before serving. This helps the sauce settle and makes serving neater. Garnish with chopped parsley for color and freshness. The final dish should be creamy, comforting, and full of flavor in every bite.