Preheat the oven to 180°C (160°C for fan forced ovens). Line 2 x 12-cup muffin pans with paper cupcake cases.
Open the cake box, remove enclosed frosting sachet and reserve for another use. Place the cake mix, eggs, oil and water in a bowl, then whisk (by hand or using an electric mixer) for 2-3 minutes until smooth and creamy. Divide the mixture evenly among the cupcake cases. Bake both trays together in the oven for 18-22 minutes. Remove from the oven and transfer the cupcakes to a wire rack to cool completely.
Place 1¼ tubs of the frosting in a bowl and beat in a little pink food colouring gel to give a pale pink colour. Spread the cupcakes with the pink frosting. Use a teaspoon to top each with a smaller swirl of the remaining uncoloured frosting.
Spray the blades of a pair of kitchen scissors with cooking oil spray and cut each marshmallow in half widthways through the thick middle, then cut each half in half again to make 4 bunny ear shapes from each marshmallow. Spray the scissors with more cooking oil spray if needed. Dip the cut side of each ‘ear’ into pink sugar sprinkles to coat. Arrange 2 marshmallow ears on each cupcake.
Use the mini chocolate beans and chocolate sprinkles to make bunny eyes, whiskers and a nose on each cupcake. Store any leftover cupcakes in an airtight container in the fridge for 2-3 days.