Prep time: 15 minutes
Cook time: about 1 hour (cooling time: 10 to 15 minutes)
Serves: about 30 squares
1 1/2 tablespoons olive oil
1 large onion, very thinly sliced
Salt and freshly ground black pepper to taste
1 tablespoon chopped fresh thyme and basil, or 1 teaspoon dried
4 thick slices cooked or smoked ham, cut into small pieces (about 1/2 cup)
2 large eggs
16 ounces low-fat sour cream
1 cup grated part-skim mozzarella or parmesan cheese
Whisk together eggs, sour cream, grated cheese, and salt and pepper; stir together egg and onion mixtures.
2. In a medium-size skillet, heat the oil over moderate heat. Add the onion, salt, pepper, and half of the herbs, and cook, stirring frequently, for about 6 minutes, or until onion is soft. Add the ham and cook another 5 minutes. Remove from the heat and add the remaining herbs.
3. Meanwhile, in a large bowl, whisk together eggs, sour cream, grated cheese, and salt and pepper. Stir in the cooked onion mixture. Pour into an 11 x 8-inch rectangular tart pan with a removable bottom or a pie plate and bake for 15 minutes (if you use a square cake pan instead, bake for 20 minutes). Reduce heat to 325 degrees and bake for another 40 minutes. Remove and let cool until warm or room temperature, about 10 to 15 minutes. Once cool, cut the tart into bite-size squares or wedges and serve with napkins.
Pre-party prep: Bake and cool tart. Slice, cover tightly with foil, and refrigerate. At the party, transfer slices to a cookie sheet; reheat in a 250-degree oven until warm throughout, about 10 minutes. PER SQUARE (a 1 1/3 x 2-inch piece): 48 calories, 4 g fat (1.8 g saturated), 80 mg sodium, 23 mg cholesterol. This tart is rich in calcium.