For the garam masala:

1. In a dry frying pan, roast all the ingredients over medium heat, stirring constantly to prevent burning. The spices are ready when the cloves well, turn gray, and pop. Allow the spices to cool, then grind to a fine powder in a spice or coffee grinder. Any unused garam masala can be kept in an airtight container for a few weeks.

For the chicken:

1. If using saffron to color the dish, in a small bowl, infuse the saffron strands in ¼ cup (60 ml) tepid water.
2. In a frying pan, heat 6 Tablespoons of the oil over medium-high heat. Add the sliced onions to the pan and fry gently, occasionally stirring until golden brown and caramelized. Using a slotted spoon, remove the onions from the oil, leaving as much of the oil in the pan as possible to use later, and place on a plate to drain. Spread the onions across the plate so they crisp as they cool.
3. In a large bowl, mix the yogurt with the garlic, ginger, 1 Tablespoon of the garam masala and the oil retained from the caramelized onions.
4. In a pan that has a lid, heat the remaining 4 Tablespoons of oil over medium-high heat. Add the chicken and sear on all sides. Lower the heat to medium and pour the yogurt mixture over the chicken. Keep the heat at medium so the contents of the pan do not boil. Add the caramelized onions and ground coriander and cook, stirring continuously, for 10 minutes.
5. When the oil rises to the surface and the yogurt splits, add the chili powder and salt. Bring the sauce to a boil, then reduce the heat. Add the infused saffron at this point. Cover and cook the chicken for a further 10 minutes. Add the sugar and stir to mix thoroughly.
6. Before serving, taste to check the seasoning and adjust as necessary.
7. To serve, garnish with sliced almonds.