Pre-heat the oven to 180º.
Grab a piece of aluminium foil (15 by 15 centimetres is more than enough) and add a drizzle of olive oil over it. Place the garlic head, cut side down, over the foil and add a pinch or two of salt. Wrap the foil around the garlic head and put it in the oven, in the middle rack. Roast for 30 to 40minutes.
In the bowl of a food processor, combine the white beans, salt, dried thyme, black pepper, lemon juice and olive oil. Squeeze the roasted garlic cloves out of their skins and add them to the bowl. Process everything until very smooth.
In a cast iron pan over medium heat, add the garlic, olive oil and red pepper flakes and fry for no longer than 30 seconds. Add the greensand gently stir everything together so that the greens get evenly wilted. Cook the greens no longer than 2 minutes and, at the very last moment, add freshly grated nutmeg.
In a separate pan, toast the slices of bread.
Spread a layer of the bean mixture over the bread slices and add the greens on top. Drizzle a bit more olive oil over each toast, if desired, and eat immediately.