Preheat the oven to 160°C and line an 8 inch cake tin with parchment.
Beat the butter, sugar, extract and zest until fluffy before adding the eggs, flour, baking powder and cream.
Whisk to combine before transferring to the cake tin.
In a bowl, mix the crumble ingredients until small nuggets form.
In another bowl combine the blueberries with the flour and sugar.
Add the blueberry mixture to the top of the cake batter, followed by the streusel topping.
Bake for 70-90 minutes until a skewer comes out clean.
Mix the icing sugar with the milk and drizzle over the top.
Slice, serve and enjoy.
