SQL Server provides the dm_exec_chached_plans DMV that can be used to get details on cached plans.
select SUM( size_in_bytes )/1024/1024. [Cache Size in MB]
select refcounts, usecounts,These queries will give you the total size of your procedure cache and which plan\query is using the most.
size_in_bytes/1000./1000. [Obj Plan Size in MB],
order by size_in_bytes desc
Next blog in the series will be how poor design can bloat the cache and how to avoid it.