To make the Mughlai Chicken dairy free I wonder if you can substitute the yogurt and cream with coconut milk?
Nigella's Mughlai Chicken (from FEAST) is a mild and creamy curry that is made with a combination of double cream and Greek yogurt. If you wanted to make the dish dairy free then we would suggest that the double cream is replaced with coconut cream and the Greek yogurt is replaced with natural (plain) coconut milk yogurt. As plant-based products can sometimes be naturally slightly sweeter than dairy products, we suggest reducing the sugar to 1 teaspoon. Once the dish has finished cooking you can taste the sauce and add a little extra sugar if you feel that it is needed.
The coconut cream should be unsweetened and should not be confused with creamed coconut (that is usually sold as a block or paste). If you can't find coconut cream then you can let a can of good quality (not light) coconut milk stand for a day and open carefully, then scoop out the thicker liquid that rises to the top. The sauce should be simmered gently and not allowed to boil as all yogurts (dairy and non-dairy) can split if they are boiled too hard.