Preheat the oven to 300°.

In a large heavy-bottomed pot, heat a ½ cup of the olive oil over medium-high heat until smoking (something with a light enamel bottom is good here so that you can see the color of the spinach and oil change). Add the spinach and sauté, stirring frequently with a wooden spoon. Continue to cook, scraping the bottom of the pot with your wooden spoon frequently, until all of the water evaporates and the spinach is blackened. The entire process will take around 35 minutes. As the spinach cooks, add two more rounds of a ¼ cup of olive oil (at about 10 and 25 minutes into the process) when the spinach starts to get overly dry and sticky. The spinach is done when it’s dark and crispy, almost black and the residual oil is a deep green. At this point you can freeze the spinach and use it to make the pkaila later.

Remove the spinach from the pot with a slotted spoon, leaving the oil from the spinach in the pot. Add the onions and a ½ teaspoon of salt and sauté until softened, about 5 minutes.

Turn the heat to low. Add the blackened spinach, garlic, thyme, cilantro, mint, cinnamon, cumin, coriander, harissa, and beans and stir to combine evenly.

Create little pockets in the mixture and plug the bone marrow in (if using). Add the lamb or beef and the sausage to the pot and cover with water or stock (about 6 cups).

Bring to a simmer, cover and place in the oven. Cook for 2-3 hours, checking occasionally and adding more water or stock if needed, until the beans and lamb or beef is tender. Season to taste and serve immediately.