Preheat oven to 160°C or 140°C fan-forced. Grease a 19cm x 9cm bar cake tin and line with baking paper.
Place water and oil into mixing bowl, followed by the Creme Muffin mix. Using a beater attachment on an electric mixer, beat together on low speed until combined. Scrape bowl and beat on medium speed for 2 minutes.
Fold through the yoghurt, lemon zest and 3/4 punnet of blueberries.
Pour mix into tin and place some blueberries on top of cake.
Bake for approximately 1 hour or until skewer comes out clean.
These instructions may vary depending on the equipment used.