Saffron chicken korma

Name: Saffron chicken korma
Ingredients: 500g Turkish or Greek yogurt (10% fat); 1 tbsp garlic paste; 2 tbsp fresh ginger paste; 8 medium skinless chicken thighs on the bone; 2 tbsp whole milk; large pinch good-quality saffron; 6 tbsp vegetable oil; 3 medium white onions, evenly and thinly sliced into rings; whole garam masala (2 Indian bay leaves, 1-inch long piece cassia bark, 3 green cardamom pods and 1 clove); 1 tbsp ground coriander; ¼ tsp chilli powder; 2 tbsp ground almonds; 1 tbsp sugar; small handful of almond flakes, to garnish