[header] How to make a marble mirror cake [title] Preheat the oven to 350 f. [step] Beat the cake mix, butter and milk on medium-high speed. Add in the eggs one at a time until fully mixed. Then, beat on high for two minutes. 
[title] Pour the mixture into a greased 9 inch cake pan and smooth out the top with a spatula. [step] Knock the pan on the counter 2 or 3 times to get any excess air bubbles out.