Need help spawning a Blueprint that inherits from a C++ UObject class

I guess what you want is create a class from a blueprint that you created in the editor?

I’ve managed this way:

static ConstructorHelpers::FClassFinder<APawn> BotPawnOb(TEXT("/Game/Blueprints/AI/BotPawn"));
DefaultBotClass = BotPawnOb.Class;

where /Game/ is your Content directory, I suppose.