In a Dutch oven or deep pot, melt unsalted butter over medium-high heat. Add in your onions and leek, and sweat them out for 5 to 6 minutes, until translucent, without bringing on any color.

Add in your garlic cloves, seasoning with salt and pepper. Give everything a good toss, and then add in your broccoli.

Let everything cook down and combine together for another 5 to 6 minutes.

Add in your broth, and bring to a simmer on medium heat until your broccoli is softened and fork tender.

Transfer to a blender, or use an immersion blender to blend until completely smooth. Season with salt and pepper. Transfer back to the pot, add in your creme fraiche, and mix well until combined.

Serve in bowls, and top with a drizzle, or dollop of creme fraiche with a big crank of black pepper.