Start by cutting the celery into thirds and arranging them on a baking sheet. Drizzle with half the olive oil and season lightly with salt and pepper. Roast at 400°F for about 30 minutes until tender and golden—it really develops that deep, rich flavor I love.
While the celery roasts, heat the remaining olive oil in your large pot. Add sliced mushrooms and sauté for 8–10 minutes, until they’re golden and slightly caramelized. Then toss in the diced potatoes and thyme, cooking just a minute to let the flavors meld.
Pour in your water or vegetable stock and bring it to a boil. Reduce heat and let it simmer for 20 minutes until the potatoes are fork-tender. This step lets the flavors combine beautifully while keeping the potatoes soft for blending.
Scoop out about half the cooked potatoes and place them in a food processor with the roasted celery and a few spoonfuls of the hot broth. Blend until smooth and creamy. This purée will give the soup its signature silky texture without using cream.
Return the soup to a boil, then stir in the celery-potato purée and elbow pasta. Cook until the pasta is al dente, about 8–10 minutes. Taste and adjust seasoning with salt and pepper—this step ensures every bite is perfectly seasoned.
Ladle the soup into bowls and garnish with fresh dill, parsley, or a sprinkle of paprika. I like drizzling a touch of extra virgin olive oil on top—it makes the soup feel extra indulgent without being heavy.