Caramelized Onion Quiche - Test 1

 https://www.simplyrecipes.com/recipes/caramelized_onion_quiche/

1 - Made once, and it was highly acclaimed. I can't remember if I switched out the nutmeg for the mustard, or if I kept one and discarded the other.

1 blind-baked pie crust, completely cooled

2 Tbsps mild veg oil

2-3 (about 1lb) large onions, French-cut (see instructions)

Salt and freshly ground pepper

2 tsps balsamic vinegar

3 large eggs

1/2 cup heavy cream

1/2 cup milk

1 tsp Dijon mustard (?)

Pinch nutmeg

6 ounces Gruyère cheese, grated (1 1/2 cups)

1. The onions will take about an hour to cook on the stovetop before they are ready to go into the quiche. So timing-wise, get started on the onions once you've put the crust in the freezer to chill before pre-baking.
2. Heat the oil in a large, heavy-bottomed sauté pan on medium heat. Add the onions and sprinkle a little salt over them. Cook, stirring occasionally for 10 minutes, until the onions have softened and are translucent. Reduce the heat to medium low and cook for an additional 40 minutes, stirring occasionally, until the onions are well browned.
3. Once the onions are well browned, pre-heat the oven to 375°F. Add the balsamic vinegar to the browned onion and cook for 10 minutes more, until onions are completely caramelized. Remove from heat.
4. Sprinkle half the cheese evenly over the bottom of the baked crust. Spread the onions over the cheese and then top with remaining cheese.
5. In a medium bowl, whisk together milk, cream, eggs (and mustard?). Season with nutmeg, salt, and pepper. Pour over the tart.
6. Transfer to the 350°F oven, and bake until just set in the center, 30 to 35 minutes. Cool on a wire rack for about 10-15 minutes before slicing.