Heat one tablespoon of olive oil in a large frying pan with a lid over medium heat. Add the crumbled chestnuts and cook, stirring occasionally, for 6 to 7 minutes, until golden and with crisp edges. When it is done take them from the pan and put on plate lined with kitchen paper so it can absorb unnecessary oil. In the meantime, in a small bowl, combine the harissa paste with the yogurt, seasoning to taste, and set aside.

Pour the other tablespoon of olive oil into the same pan. Add the cumin seeds and cook them gently, letting them release their fragrance without burning. After a minute, add the sliced red onion and sauté for about 10 minutes, stirring periodically, until softened. Then add the minced garlic and sliced chili, cooking for another 2 minutes to open up their flavors.

Raise the heat to medium and add the shredded Brussels sprouts. Stir from time to time and cook for 8 to 10 minutes until they start to soften. When tender, add the spinach and stir until wilted, then season the mixture to taste.

Reduce the heat to medium-low and make four small wells in the sprout mixture. Crack an egg carefully into each well, cover the pan with a lid or foil, and cook until the egg whites are set and the yolks are still slightly runny, 5 to 8 minutes.

To serve, spoon the harissa yogurt over and top with the crispy chestnuts. Serve, with any reserved harissa yogurt on the side, for a flavor boost