• Preheat the oven to 400°F (200°C).
• Place the butternut squash on a baking sheet and drizzle with oil. Toss well to coat the pieces evenly, then roast for 20 to 30 minutes, until tender.
• Heat 3 tablespoons of oil in a large saucepan.
• Add the onions and cook over medium heat for 10 minutes, until softened. Stir in the garlic, reduce the heat, and continue cooking for a few more minutes.
• Meanwhile, toast the cumin and coriander seeds in a dry pan over low heat for about 1 minute, until fragrant.
• Crush the seeds using a mortar and pestle or a spice grinder, then add them, along with the cinnamon, to the saucepan with the softened onions. Cook the spices for a few minutes to release their aromas.
• Add the lentils along with 1 liter (about 1 quart) of just-boiled water. Cover and let simmer for 10 minutes.
• Once the lentils begin to soften, add the roasted squash, the stock, the lemon juice, 1 teaspoon of salt, and 1/2 teaspoon of black pepper. Let the soup simmer for another 10 minutes.
• When the lentils are fully cooked, remove the saucepan from the heat and blend the soup using an immersion blender. Taste and adjust the seasoning to your preference.

To prepare the za’atar croutons

• Roughly cut the bread into pieces about 1 inch (2.5 cm) wide.
• Heat 3 tablespoons of oil in a frying pan. When hot, add the bread and sprinkle with the za’atar.
• Cook, stirring frequently, until the croutons are golden and crispy. Transfer them to paper towels to absorb any excess oil.

To serve

• Ladle the soup into warmed bowls, top with the croutons, then finish with a drizzle of extra-virgin olive oil and a pinch of chopped fresh herbs.