Preheat the oven to 425 degrees F.

Toss asparagus with 1 tablespoon olive oil, 1/2 teaspoon kosher salt, and 1/4 teaspoon black pepper on a sheet pan. Spread into a single layer and roast for 8 minutes until bright green. Reserve about 10-12 asparagus tops for garnish.

In a large saucepan or Dutch oven, heat 1 tablespoon olive oil over medium heat. Add chopped onion and sauté for 5 minutes until they start to soften.

Stir in minced garlic, 1/2 teaspoon kosher salt, and 1/4 teaspoon black pepper. Continue cooking for about 1 minute until fragrant.

Add the roasted asparagus, diced potato, baby spinach, and vegetable broth to the saucepan. Bring to a boil, then reduce heat and let simmer for 15-18 minutes, or until potatoes are tender.

Transfer the soup in batches to a blender and puree until smooth, or use an immersion blender directly in the pot.

Return the pureed soup to the saucepan to reheat if necessary before serving. Divide the soup into bowls and garnish with reserved asparagus tops, chopped parsley, flaky sea salt, and additional black pepper as desired.