1 whole wheat pie crust, chilled
2 yellow onions, chopped
1 teaspoon fresh thyme leaves
2 tablespoons butter
1/2 bunch Swiss chard, ribs removed, leaves chopped (about 2 1/2 cups)
1 cup half and half
4 large eggs, beaten
1 teaspoon salt, plus more for seasoning
1/4 teaspoon black pepper, plus more for seasoning
1 pinch fresh ground nutmeg
Heat a large non-stick pan to medium high and add chopped onions. Cook until browned but not burnt, about 6 minutes. Add a tablespoon of butter, the fresh thyme, and sprinkle with salt and pepper. Lower the heat to medium and continue to stir while cooking. Add the remaining tablespoon of butter when the onions become dry and start sticking to the pan, about another 5 minutes.
Once the onions are evenly caramelized, about another 5 minutes, add the chopped chard and sauté until wilted, about 2 minutes. Remove from heat and cool.
Preheat to 425°F. In a medium bowl, whisk the half and half, beaten eggs, salt, pepper, and nutmeg together.
Mix in cooled onion and chard mixture. Pour filling into crust. Place the quiche on a baking sheet to make it easier to transport and in case the filling overflows in the oven.
Bake quiche for 15 minutes. Reduce heat to 350°F and bake until filling is puffed and just set in center, about 10-15 minutes longer. Transfer to rack and cool 10 minutes. Serve hot or at room temperature.
You can freeze the quiche after it has cooled. To reheat, place in a preheated 350°F oven for about 30 minutes, until heated through.