I have to agree with Warsaw Will and Jasper on the subject-verb agreement in terms of singular vs. plural. In my opinion "five eggs IS too much" is perfectly fine just as the singular form is correct for the other examples Warsaw Will gave; this is because our minds subconsciously fill in additional words that are a part of the sentence structure, but not said out loud:

'[A distance of] Five miles is a long way to walk for a young child.'
'[A payment of] Ten pounds is a lot to pay for what is basically a sandwich.'
'[Weight of] Twenty kilos is about the same weight as two buckets of water.'
'[The amount of] Thirty cigarettes a day was about his average.'

I also agree that, in my mind, the eggs are a part of a liquid amount because they all go into the same bowl, in which the content increases and decreases by adding or subtracting an egg, just as the can of gasoline increases and decreases by one or two gallons of gasoline. Which is why "too much" sounds correct and according to grammatical rules, even though it is technically probably not grammatically correct.