What kind of chocolate?

Does it matter?
Not in the sense that only a particular chocolate will make or break the pie.
But yes, in the sense that choosing a key ingredient where there are only a few key flavors is important yes.
Probably either milk or dark chocolate would work here, and the higher the percentage of cocoa solids the richer the taste.
Read the comments and adjust your quantities or pie plate - there is some disconnect in the original about quantities and size of baking dish.