By Chris Ross / The San Diego Union-Tribune

Natalie Coughlin is best known for her athletic achievements. Competing as a swimmer in the 2004, 2008 and 2012 Olympics, she won three gold medals, four silvers and five bronze medals. What’s less known about her is that she’s an experienced and passionate home cook.

Coughlin has been a judge on “Iron Chef America.” She also competed in a 2013 version of “Chopped” that featured sports stars, losing in the final round to Danica Patrick. She says she has cooked for herself during her entire swimming career, “developing a diet that could sustain my body for the long term, through demanding training seasons and intense competitions.”

Her first cookbook, “Cook to Thrive,” is a collection of her personal recipes, both “performance-rated dishes” from her Olympic competition days and treasured family recipes.

Coughlin raises chickens at her home in Northern California. With all those eggs, she says she makes a frittata at least once a week.

Asparagus and sweet onion frittata

1 pound asparagus, trimmed

2 tablespoons extra virgin olive oil, divided

Kosher salt and freshly ground black pepper

10 large eggs

1 (5.2-ounce) package Garlic & Herb Boursin cheese

1 tablespoon unsalted butter

1 large sweet onion, such as Vidalia, thinly sliced (about 2½ cups)

Preheat the oven to 425 degrees.

Place the asparagus on a rimmed baking sheet and drizzle with 1 tablespoon of the olive oil. Season with a hefty pinch each of salt and pepper. Roast until the spears are cooked through but still have some bite, about 10 minutes (if the spears are quite fat, you may need to cook them longer). Remove from the oven and let cool slightly. Coarsely chop the asparagus into bite-size pieces.

Reduce the oven temperature to 300 degrees.

In a large bowl, whisk together the eggs, 3 tablespoons of the Boursin cheese, ½ teaspoon salt and ½ teaspoon pepper (the Boursin will be pretty chunky; don’t worry about whisking it smooth).

Heat a large cast-iron or other ovenproof skillet over medium heat. Add the butter and remaining 1 tablespoon olive oil to the pan. When the foaming subsides, add the onion. Cook, stirring occasionally, until the onion is translucent and soft, about 5 minutes. Add the asparagus and the egg mixture to the skillet and cook, undisturbed, for 1 minute.

Transfer the skillet to the oven and bake until the eggs are just barely set and jiggle slightly when you shake the pan, 20 to 25 minutes. Remove the pan from the oven and use an offset spatula or a knife to release the frittata from the sides of the pan.

Let the frittata cool for 5 minutes before transferring it to a large platter. Slice it into wedges and slather a tablespoon of the Boursin on each slice before serving.

— Reprinted from “Cook to Thrive: Recipes to Fuel Body and Soul” by Natalie Coughlin. Published by Clarkson Potter, an imprint of Penguin Random House, LLC.