Okay, we secretly call this "80s Potluck Dip." Remember? With that sweet Hawaiian bread? And the Knorr soup mix? Yum. This version is healthier — with wheat bread, no MSG, extra spinach, and yogurt and cottage cheese swapped in for some of the mayo — but it's still totally scrumptious. If your children are repulsed by spinach, then don't let them wring it out — a process whereby a large soupy packet of vegetable turns into a fist-size ball of green dryer lint — but otherwise, this is a fun job. As is hollowing out the loaf, since the fact that the bowl is really bread — and you can tear it up and eat it afterward — will blow your kids away. Dinner's a party when appetizers become the main course.
Heat oil in a wide frying pan over medium heat and saute onion with salt, stirring frequently, until it's very nicely browned, about 15 minutes. Add garlic right at the end, and saute, stirring, another minute before turning off the heat.
Meanwhile, in a food processor whir together yogurt, cottage cheese, and mayonnaise until smooth. Add the slightly cooled onion mixture and spinach, and whir until nearly smooth.
Scrape dip into a bowl, stir in water chestnuts, then season to taste with pepper, a squeeze or two of lemon juice, and more salt.