Saute 1 chopped onion, 2 minced garlic cloves and 1 teaspoon fresh thyme in 2 tablespoons butter in a large pot over medium-high heat until softened, about 5 minutes. Add 2 pounds asparagus (trimmed and chopped), 1 1/2 cups each water and chicken broth and a big pinch of salt. Simmer until tender, 5 to 8 minutes. Working in batches, puree in a blender. Return to the pot, whisk in 1/2 cup crème fraiche and warm through (do not boil). Season with salt and pepper. Top with more creme fraiche and chopped chives.