Grease the baking tin with the butter and sprinkle the brown sugar evenly in the base. Arrange the fruit in an even layer on top of the sugar.
In a medium bowl, whisk flour, baking powder, and lemon zest.
In a large bowl, using an electric mixer beat oil and sugar until light and fluffy. As you continue beating, add in the curds.
Add the flour mixture to the wet ingredients alternating with milk, starting and ending with flour mixture. Beat until smooth.
Preheat the oven at 185C.
Carefully pour the batter over the arranged fruit and bake at 185C for 30 to 40 minutes until the top is golden-brown.
Let the cake rest in the tin for 10-15 minutes before taking it out.