Warm onion-potato gratin

All month long I have had an unusual hankering for a good cheesy gratin. This one turned out pretty good. Next time I may caramelize the onions a bit and perhaps throw in some crumbled bacon to doctor it up, although it is fine as is...

Warm onion-potato gratin (from epicurious.com):
*1 cup (packed) grated Gruyere cheese (about 4 ounces)
*8 tablespoons (packed) freshly grated Parmesan cheese (about 2 ounces)
*2/3 cup whipping cream
*1 1/2 pounds Yukon Gold potatoes, peeled, cut into 1/4-inch-thick slices
*3/4 pound onions, thinly sliced

1. Combine Yukon Gold potatoes and sliced onions in heavy large saucepan. Add enough water to cover. Bring water to boil. Reduce heat and simmer until potatoes are almost tender, about 3 minutes. Drain potato-onion mixture well.

2. Arrange half of potato-onion mixture in 11x7-inch glass baking dish. Sprinkle with salt and pepper. Sprinkle mixture with 1/3 cup Gruyere cheese, then 2 tablespoons Parmesan cheese. Arrange remaining potato-onion mixture atop cheeses. Pour cream over. Sprinkle with salt and pepper, then remaining 2/3 cup Gruyere cheese and 6 tablespoons Parmesan cheese. (Can be prepared 8 hours ahead. Cover and refrigerate.) Preheat oven to 400 degrees. Bake gratin uncovered until cream thickens, about 25 minutes. Remove from oven. Preheat broiler. Broil gratin until top is golden, about 2 minutes.

I didn't know how many potatoes and onions constituted 1 1/2 lbs and 3/4 lbs respectively, and was too lazy to measure out the listed amounts of cheese-so I just threw in a lot of potatoes, a lot of onions, and A LOT of cheese. And extra cream to make the right consistency. And I wonder why the top button on my jeans is a hairy endeavour.