Preheat your oven to 400°F (200°C).

In a large mixing bowl, combine the chopped butternut squash, parsnips, carrots, and fennel. Drizzle with olive oil and sprinkle with salt, then toss to coat.

Spread the seasoned vegetables in a single layer on a baking sheet lined with parchment paper and roast for about 40 minutes, stirring occasionally.

While the vegetables roast, heat a tablespoon of olive oil in a large saucepan over low heat. Add chopped onion with a pinch of salt and pepper, sautéing for about 10 minutes.

Once the onions are soft, add flour to the saucepan and stir continuously for 3 minutes.

Gradually pour in the vegetable broth, then add peeled and chopped potatoes and thyme. Increase the heat to medium and bring to a gentle boil.

Reduce the heat and let the soup simmer uncovered for about 15 minutes.

Carefully blend about 3 cups of the mixture until smooth. Return it to the pot with the remaining unblended mixture.

Stir in milk and heat on low until it reaches a gentle simmer.

Taste and adjust seasoning with salt and pepper as needed. Serve garnished with cracked black pepper and fresh thyme.