Jennifer McLagan's cookbooks are joyously contrarian affairs. In 2005, she published the finger-licking and terrific "Bones." Now she has "Fat." This is no quick-and-easy book featuring chicken cutlets with breakfast cereal "crust." It's a rollicking journey through the kingdom of unrepentant, glorious, and filthy rich fat.

In her carefully presented introduction, McLagan argues that fat is healthy, unrivaled for cooking, and satisfying, so you eat less of it. A week of testing left me convinced this was true, except for the "eating less of it" part. Though we are as civilized as any group including two small children can be, all week there was frequent, raucous fighting over whatever was left in the pan. McLagan has a superb sense of balance on the plate; she knows how to use bitter greens, bright acids, sharp-tasting herbs to cut the overwhelming decadence of fat.

The book's four sections are dedicated to butter, lard or pork fat, poultry fat, and beef and lamb fat. For any fat-fearing cook, the first will likely prove the most approachable, not least because butter's there in a box on the refrigerator shelf. You don't have to go rummaging around in animal cavities to collect it. McLagan has a fat lover's reverence for the fresh herb sage; acrid and wooly, sage sweetens and brightens when cooked. Its robust flavor stands up to the richest of foods, as is demonstrated by spaghetti with butter and sage. I wouldn't normally douse a half-pound of pasta with a stick of butter, but I'm glad I did. The butter is both a lubricant and a sauce, and the quantity seems surprisingly light on the plate.

Equally hard to resist is poached shrimp with spinach and the French butter sauce beurre blanc. A poaching liquid, deeply flavored with bay leaves, parsley, onion, lemon, and vermouth, gives the shrimp character to stand up to the buttery sauce. The grassy spinach perfectly complements the extra butter.

I had a feeling spicy buttered popcorn would be addictive - and it is. Eight cups of popcorn isn't quite enough to absorb nearly a pint of frothing, chipotle-caramel sludge, and even with 10 extra minutes in the oven, parts of it didn't dry out.

If you have reservations about bacon fat, stay away from smokily seductive pumpkin and bacon soup (in fact, maybe stay away from this book altogether). It's one of those rare cases where you need all the fat rendered from half a pound of bacon to brown the aromatics, and for the intense bass drum of flavor it provides the soup's base of squash and sage.

Perhaps the best case for fat is McLagan's slow-roasted pork belly. Pork belly is bacon before it's bacon; here it gets an overnight marinade and a slow roast, until the fatty meat is almost translucent. Then the skin is broiled to a golden crisp, a perfect foil to slightly bitter kale.

Spanish-style lard cookies are a happy reminder that butter's not the only baking fat. The toasted-flour-and-almond dough wins no beauty prizes. But the delicate scent of oranges and cinnamon and the delightfully crisp texture make these a versatile delicacy.

My supermarket had marrow bones, so I tried risotto Milanese - insanely, pleasurably rich with butter, marrow, and Parmesan. Bones contain wildly variable amounts of marrow, and mine yielded so much the rice couldn't absorb it (it might have helped to have a volume or weight estimate).

I can't pretend I relished the suety smell on my clothes and in the kitchen after the marrow-bone adventure. And I hope it's not every week that I go through five sticks of butter, four pounds of bacon, three cups of marrow, and a half-cup of lard. But when I do plunge into these riches, I plan to have McLagan at my side, to make sure every ounce is worth it.

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