Soak the chickpeas in cold water with bicarbonate of soda overnight (approximately 12-18 hours).

Drain and rinse the soaked chickpeas.

Combine the chickpeas with 2 1/2 quarts of water in a large saucepan.

Bring to a boil, then reduce heat to low and simmer for 2 hours, or until chickpeas are tender.

Every 10 minutes during simmering, add 1/2 cup of cold water to slow down the cooking process.

Continue simmering until the water has reduced and barely covers the chickpeas.

Turn off the heat and let the chickpeas sit in the remaining water.

In a small sauté pan over medium-low heat, brown the garlic cloves in olive oil for about 3 minutes. Remove garlic and set aside.

Add the bread to the pan and brown on both sides, about 1 minute per side. Remove and set aside.

Remove the pan from the heat and let it cool slightly.

Add the pimenton and saffron to the pan, then immediately add sherry vinegar to prevent burning.

In a mortar, smash the reserved browned garlic and bread into a thick paste.

Bring the chickpeas back to a low boil.

Add the spinach and simmer for 5 minutes.

Add the pimenton mixture and the garlic and bread paste to the chickpeas.

Simmer for another 5 minutes, allowing the sauce to thicken.

Season with salt and pepper to taste.

Serve immediately.