Microwave butter in large microwaveable bowl on HIGH 1 to 1-1/2 min. or until melted. Add cake mix and 1 egg; beat with mixer until well blended. Press 2/3 of the mixture onto bottom of prepared pan.
To make the cake, combine the flour, baking powder, bicarbonate of soda and salt in a large bowl. Whisk the oil, sugar and coconut milk together in a jug, followed by the lemon zest and 3 ...