Roughly chop plums. Grind together arrowroot biscuits, brown sugar, butter and cinnamon powder and transfer the mixture into a bowl.
Mix together sugar and plums in a non-stick pan and cook for 7-8 minutes or till the mixture becomes pulpy. Transfer into a bowl and cool over an ice-bath, stirring continuously. Add almonds and hung yogurt and mix well.
Fill 4 glasses with the biscuit crumble keeping aside some for garnishing. Top it with the plum mixture. Spread the remaining biscuit crumble over it and serve.