Heat olive oil in a large pot over medium heat. Cook and stir garlic in hot oil until fragrant, about 1 minute. Stir chicken broth, cauliflower, cayenne pepper, salt, and black pepper into garlic. Bring to a simmer, reduce heat to medium-low, and cook until cauliflower is tender, about 15 minutes.

Stir 2 pounds asparagus into cauliflower mixture and increase heat to high. Cook until asparagus is tender but still bright green, 5 to 6 minutes.

Blend soup with an immersion blender until smooth; season with salt and black pepper. Ladle soup into bowls and garnish with flower petals and diced asparagus tips.