I've always believed that your "big gift" on Christmas should change your life in some way. It could be a slinky black sweater that transforms you into a femme fatale, an exercycle that forces you to raise your heartbeat, a datebook that organizes your life, or a Cabbage Patch doll that turns you into a motherly sort.

Easy enough when you're a kid and your life changes every six weeks anyway. Harder when you're a grown-up in a rut. I'm pleased to say that such a boon came to me this Christmas after months of hinting -- my very own microwave oven.

I was convinced we needed such a thing because the five of us eat different things and are always tearing off in different directions; a full-time cook and bottle washer could easily be kept scurrying from dawn to way past dusk serving our every need. Nobody had volunteered for this job, so we needed time-saving help.

Friends and relatives had showed me marvelous heating tricks with their microwaves, like the old heat-a-cup-of-coffee trick and grandfather's favorite, the microwave-a-bag-of-popcorn trick. Since we heat a lot of things at our house -- hot dogs, soup, leftovers, and the meal cooked at 5 and consumed at 8, I thought a microwave for reheating things was just the ticket.

I don't think anybody ever told me you actually could cook in the microwave oven, and that's what changed my life. The true wonder of the microwave is not its speed, but its ability to cook things in their serving dishes, which means, oh wonder, oh joy, no pots and pans! I had been repressing how much I hated washing pots and pans until I started living without it. Suddenly, I was leaving the kitchen 20 minutes sooner at night. Weekday lunches, once cold and rudimentary for speed, suddenly became hot -- cheese melted on tuna instead of plain cold tuna -- and there were still no pots and pans.

And on the days when I am very, very organized (I've long fantasized about this), I can cook the grown-up dinner at 5 as usual, load it right onto plates, wash whatever bowls or pots were used while the children are eating, and just stuff the plates into the microwave to reheat at 8 o'clock, grown-up dinner time. Then we can just plunk the plates in the dishwasher and go straight to bed.

Have I mentioned the defrosting function? It is no longer necessary at our house to put the frozen chicken parts or steaks out in the morning; to contemplate dinner at breakfast time even as you are packing everybody's lunch. Just last Saturday, at 3 p.m., we invited the neighbors over for dinner, defrosted the steaks in 10 minutes' time, made the following broccoli with cheese sauce in the microwave, and late that night had only a skillet and salad bowl to wash by hand.

But it is Christmas dinner that I remember with the most fondness. As the ham roasted in the conventional oven, the Family Cook made creamed onions, wild rice and mashed turnips in their own serving dishes in the microwave. I knew then I'd gotten the best Christmas present in many years: the gift of time and tranquility. There is no more bang, crash, bang of hasty and angry pot rattling in my kitchen. When the Family Cook is at work, one hears the space-age, serene beep-beep of her computerized, electronic pal, and a great deal of happy humming.

I'm still learning on my microwave, but these recipes I consider nothing short of miraculous. They may not be faster than the old-fashioned way, but they seem easier and easier to clean up. FUSS-FREE SHRIMP (4 servings)

These are low-calorie because they're steamed, easy on the cook because you shell them as you eat them, and provide the kitchen a pleasant seaside scent rather than a heavy smell of fish. 1 1/2 pounds unpeeled raw shrimp 2 1/2 cups water 1 bay leaf 1/4 teaspoon cayenne 1 tablespoon vinegar

Place everything in a 2-quart glass casserole dish. Cover with plastic wrap. Microwave on high for 6 to 10 minutes. Serve with cocktail sauce. BROCCOLI WITH CHEESE SAUCE (4 servings) 1 head broccoli, cut in spears 1 teaspoon salt 1 tablespoon lemon juice 2 tablespoons butter 2 tablespoons flour 1 cup milk 1 cup shredded cheddar cheese

Arrange broccoli in a circular dish with flowerets in the center and stems pointing out like spokes. Add 1/4 cup water and 1/2 teaspoon salt. Sprinkle on lemon juice. Cover with plastic wrap, leaving 1 inch of dish's edge exposed to allow steam to escape. Microwave on high for 15 minutes. Check for desired doneness. Microwave 3 minutes more if necessary.

In a 1-quart serving bowl, place butter, flour and remaining salt. Microwave on high for 1 minute, stir and microwave for 1 more minute. Remove bowl from oven and gradually stir in milk. Microwave at high for 4 minutes, stopping to stir every minute until sauce is thick and bubbly. Add cheese and stir until melted. Drain broccoli and add sauce. Toss. MICROWAVED VEGETABLES WITH CHICKEN (4 servings) 1 tablespoon oil 1 tablespoon butter 3 medium onions, quartered lengthwise 3 cups sliced cabbage 3 carrots, skinned and sliced diagonally 1 bunch scallions, sliced 1 cup cauliflower flowerets 3 stalks celery, diagonally sliced 1 pound fresh pea pods 1 whole skinned, boned chicken breast 2 tablespoons sesame seeds

In a 3-quart casserole, place oil, butter and onions. Microwave on high about 1 minute or until butter is melted. Stir in remaining vegetables and microwave on high for 4 minutes. Remove, stir again, and place on a platter. If chicken is frozen, microwave it on the defrost setting (low) for 3 minutes until it is partially defrosted. Slice into strips, and quickly brown them in a small skillet. Arrange the strips on the cooked vegetables, sprinkle with sesame seeds. Cover with plastic wrap and reheat in the microwave on high for 2 minutes.