Another way of saying: 'I want to have my cake and eat it' is 'I am incapable of taking a decision'. Big political decisions usually involve making painful choices. Take Covid. The harder you lock down, the more you'll limit the spread of the virus, but the more damage you'll do to the economy.
The UK was late in imposing both of its lockdowns. Was this because Boris Johnson was incapable of taking the tough decision about how you balance economic damage against saving lives? Certainly, plenty of people complain about his indecisiveness when he was Mayor of London.
Brexit involves equally painful decisions. The more distant you want to be from the EU, the more damage you do to jobs, businesses and public services, and the greater the danger that you will break up the UK.
Johnson still seems not to have progressed from cakeism. He's still telling the dwindling band of people who believe him that we can have the benefits of EU membership without the responsibilities. The UK has tried demanding this for the last four years without success, but with perhaps just a week left to secure a deal, Johnson seems to have no fresh ideas.
Even if authoritarian nihilist Dominic Cummings has really departed, it will make the central decision no easier. What does the UK want: more distant and poorer, or closer and better off? With time running out, if Johnson continues to prevaricate, we will end up with no decision. And that will mean no deal. And that will mean we won't be able to have our cake or eat it.