I have done it a few times.

I like to keep it simple and convenient without any cooking involved.

I have three coffees a day and i put 2tbsp (100cal) worth of cream in
each. That's 300cal
I measure out ~8oz of cream cheese that is (depends on brand)
800 cal. Liberally salt my cheese to avoid feeling week.
I eat a few bites whenever I feel hungry throughout the day.

This gives me ~1100cal
Very simple, no fuzz, travel/work friendly. Perfect for a short 3 day fat fast.