Swiss Onion Tart

I've made this tart for close to for 50 years and while I've tried others - including my beloved Julia's quiche Lorraine - this one always calls me home. It's simple to make and as close to fool-proof as a custard can be. The original recipe, which first appeared in Better Homes and Gardens magazine, appealed to me because it used a crumb crust. At some point I substituted a buttery pie crust for the crumbs and that added another dimension to an already delicious entree. We like this so well that I've developed another version of the pie that uses smoked salmon instead of bacon and over the years I've experimented with various types of cheese, including some combinations that make a lovely Southwestern-style tart. This makes a great entree for lunch or a light supper. It can also be cut into squares and served with cocktails. I hope you'll try this.

Swiss Onion Tart

Ingredients:
Crust:
1 pie crust
......or........
1 cup finely crushed cracker crumbs
1/4 cup melted butter
Filling:
6 slices smoked bacon
----------or----------
4 ounces smoked salmon
3 tablespoons canola oil (optional)
1-1/2 cups chopped onion
2 cups (8-oz.) Gruyere cheese, shredded
2 large eggs, slightly beaten
3/4 dairy sour cream
1/2 teaspoon kosher salt
1/2 teaspoon fresh ground black pepper
1 cup (4-oz.) sharp cheddar cheese, shredded

Directions:
1) Preheat oven to 375 degrees F. If using crumbs combine with butter and pat into a 9-inch pie plate. If using a pie crust fit into a 9-inch tart pan with a removable bottom. Set aside.
2) If using bacon, fry in a medium saute pan until crisp. Transfer to paper toweling and crumble. Pour off all but 3 tablespoons bacon drippings. If using salmon, shred and set aside.
3) Saute onions in reserved bacon drippings or 3 tablespoons canola oil until limp and caramelized. Cool slightly.
4) Place Gruyere cheese, sour cream, eggs, salt and pepper in a large bowl. Add bacon or salmon and onions. Mix well. Pour into shell. Sprinkle top with cheddar cheese.
5) Bake in lower third of oven for 30 minutes, or until knife inserted into center of custard comes out clean. Let stand for 10 to 15 minutes. If using a tart pan carefully remove sides prior to serving. Yield: 6 servings.