Thats not really possible, regardless of UE4 fancy magic C++ is still C++, not a scripting language. In the past there was myth flying around in UE4 community that blueprint generates C++, which is false, blueprint is compiled to virtual machine code which based on it, run time code in engine execute call to native code. C++ is a code that is compiled to machine code (machine-readable assembler you could say) which is directly executed by CPU when you run your code (thats why it crashes instead of giving you error when something goes wrong). Blueprints don’t exist in that space, thats why there no way to call anything from C++ to Blueprint with just simple function call, you would need to make a function that does that and then call that function (which is what UHT generates when you use ImplementableEvent) and thats just simpler issue, because blueprint as C++ class don’t exist either, it exists as instance of UBlueprint or UClass and because they are not C++ class you can’t inherit from it, or rather there no way standard compiler would able to do that.
, thats why it does nto exist in machine code space.