Ingredients:

2 tablespoons extra-virgin olive oil

1 teaspoon fennel seeds

1 medium yellow or white onion, roughly chopped

2 garlic cloves, roughly chopped

2 teaspoons kosher salt, or more to taste

Freshly ground black pepper

2 pounds asparagus, tough ends removed, chopped into 1-inch pieces (about 4 cups)

4 tablespoons unsalted butter

5 cups low-sodium chicken stock

1 cup packed fresh spinach leaves

Leaves from 1 bunch of tarragon (about 1/3 packed cup), plus a small handful for serving

1/3 cup heavy cream

Crème fraîche, for serving

IN A LARGE HEAVY-BOTTOMED POT,

Combine the olive oil and fennel seeds and toast the seeds over medium heat, stirring frequently, until fragrant, about 1 minute. Add the onion, garlic, 1 teaspoon of the salt, and a few cracks of pepper and stir again. Cook until the onions are translucent, 4 to 5 minutes.

Add the asparagus, the remaining teaspoon of salt, and a few cracks of pepper and stir to coat the asparagus. Stir in the butter, tossing the asparagus until the butter has completely melted. Pour in the stock, bring the mixture to a simmer, and cook until the asparagus is tender yet still crisp, 4 to 5 minutes. Remove the pot from the heat and stir in the spinach and tarragon. Working in batches if necessary, carefully add the hot soup to a blender and blend the soup until completely smooth. Set a fine mesh strainer over the pot and pour the soup through it. Stir in the cream and taste, adding more salt and pepper if needed.

Gently reheat the soup if it is no longer hot, then serve garnished with dollops of crème fraîche and tarragon leaves.