I love going to the market without a plan and that's exactly how this recipe was born. Spring onions were one of the first things that caught my eye. Soup was the first thing to come to mind. I had recently cooked with turnips for the first time and decided that their subtle flavor in combo with another spring favorite - fennel - would compliment the onion flavor nicely. I chose bacon to round out the recipe, a nice hit of salt and meat. —mattyeats
Place the turnips in a 12qt stock pot and add water until they can be submerged by at least 2 inches. Over high heat, bring the pot to a boil, season generously with salt and cover. Cook for 8-10 minutes, remove lid and begin checking for doneness every 2 minutes. Remove the turnips when they become just fork tender. Let them rest until they've cooled enough to handle, at least 15 minutes. Rinse the pot to use for the next step.
While the turnips are cooling, place the olive oil, spring onion and fennel in the stock pot set over medium heat. Season with salt and pepper and cook, stirring occasionally, until the fennel and onions are sweet, fragrant, and just becoming translucent, about 7-8 minutes.
Add 4 cups of chicken stock, turn the heat to medium-high, and bring to a simmer. Reduce heat to medium-low and simmer for 5 minutes. Remove the pan from the heat and set aside.
To remove the thin skins on the cooked turnips, simply wipe them away with a clean dish towel or paper towel. Cut the turnips into quarters and lightly mash them in a bowl with a fork or a potato masher. You can also use a food mill if you have one. Season with salt and pepper.
Add the mashed turnips and the heavy cream (if using) to the onion and fennel mixture and blend, using an immersion blender, until smooth. If you don't have an immersion blender, you can do this in small batches in a regular blender. If you like your soup a bit thinner, add some of the reserved chicken stock.
Serve in soup bowls and garnish with the crumbled bacon, chives and the garlic crostini.
For the Garlic Crostini
Place the Olive Oil and the smashed garlic cloves in a small saucepan over low heat. Allow mixture to heat thoroughly until the garlic becomes fragrant and light brown. Remove from heat and discard the garlic cloves.
Arrange the sliced bread on a baking sheet and lightly brush with the olive oil. Sprinkle lightly with kosher salt and toast under the broiler until golden brown on both sides, being sure to flip the slices half way through.