Count function based on multiple columns

Working on a formula I thought would be easy but it is perplexing me.
The attached workbook has 3 columns and trying to count unique occurrences in Column E (Products Delivered) based on values in columns C and D.

I thought COUNTIFS could work but each criteria needs a value to search for. I thought SUMPRODUCT might work but it won't identify the unique value number I am looking for?

Any advice helps. Thanks!