A high-speed blender not only cooks and purees the carrots at the same time, but also perfectly emulsifies butter into the soup, which adds richness and velvety texture.
How to Make It
Combine carrots, broth, 1 cup water, harissa paste, and salt in a high-speed blender. Pulse until carrots are finely chopped, about 1 minute. Gradually increase speed to high, and puree until soup is smooth and steaming, 6 to 7 minutes. With blender running, gradually add butter pieces, and puree until soup is emulsified, about 1 minute.
Heat oil in an 8-inch skillet over medium until shimmering, 1 to 2 minutes. Add almonds and rosemary, and fry, stirring often, until sizzling stops and rosemary is crisp, 30 to 45 seconds. Remove from heat. Using a slotted spoon, transfer almonds and rosemary to paper towels to drain. Reserve oil.