Preheat the oven to 375 degrees F.
Add olive oil to a large, oven-safe pan and turn heat to medium-high. Once hot, add chopped white onion and let simmer for 2-3 minutes.
While the onion is cooking a bit, slice the baguette and add butter inside each piece. Place on a baking sheet and set aside.
Once onion is fragrant, add cumin, paprika, cayenne pepper, and salt and pepper to the pan and stir. Add the full can of tomatoes and mush/loosely chop up the whole tomatoes with a wooden spoon to release their juices. Stir and reduce heat to low. Let simmer for 10 minutes or until tomato juices have thickened.
Stir in the spinach until wilted.
Create a little "well" inside the tomato juices and crack an egg into it. Do this 3 total times for each of the eggs.
Place the oven-safe pan in the oven to cook the eggs a little bit, for 5-7 minutes. Place the baking sheet with the baguette in the oven at the same time.
Once the egg whites are no longer transparent and set, take the pan out of the oven and top with crumbled feta, chopped herbs, pine nuts and sliced avocado.
Make the yogurt by mixing in the chili crisp or sambal oelek.
Serve the shakshuka with the grilled bread, hot sauce, and spicy yogurt.