Best practice to save object in cache

I'm using Redis as a cache service (Key=>Value) @ AWS ElastiCache.

I want to save an object which contains nested objects inside the cache:

• Object1 - contains instance of Object2

I'm obviously serialising my objects - let's say to JSON for that matter - so my serialised object looks like this:

{
 "property1":"property1",
 "property2":"property2",
 "property2":"property3", 
 "object2":{ 
       object2
        }
}

I'm wondering what will be the best practice from the following options:

1. Store under my key the whole object1 as a full JSON.
2. Store object2 with its own key and in my object1 serialisation to put object2 key as a reference, and when pulling back from the cache, to pull object2 through its key as well.

My guts feels that option 1 is the best practice and the most efficient, but I have second thoughts storing big nested objects under on key.