Preheat the oven to 180°C (160°C for fan forced ovens). Line 2 x 12-hole muffin pans with paper cupcake cases.
Open the cake box, remove enclosed frosting sachet and reserve for another use. Make up the cake mix as directed on the box using the eggs, oil and water. Divide the mixture evenly between the cupcake cases. Bake both pans together in the oven for 18-22 minutes. Remove from the oven and carefully transfer the cupcakes to a wire rack to cool completely; about 30 minutes.
To decorate, put the frosting in a large bowl and colour with the yellow food colouring paste or gel to give a striking sunflower yellow colour (see Tips). Spread a thin layer of the frosting over the cupcakes. Spoon half of the remaining frosting into a piping bag fitted with a small star nozzle. Pipe 6 lines from the centre of each cupcake, out to the edge, making an evenly spaced, ‘spoke-like’ pattern on each. To create the petals, start in the centre and pipe a loop by going down 1 side of each spoke, turning at the edge of the cupcake and following the next spoke back into the centre. Repeat to create 6 loops, filling the piping bag with the remaining frosting, as required.
Fill the centre of each cupcake with chocolate baking chips, pointed-side down. Serve immediately and store any leftover cupcakes in an airtight container in a cool place for 2-3 days.