The following code using a single FRotator:
FRotator CurrentRotation = GetOwner()->GetActorRotation();
UE_LOG(LogTemp, Warning, TEXT("%s"), *CurrentRotation.ToString());
UE_LOG(LogTemp, Warning, TEXT(“Yaw: %f”), CurrentRotation.Yaw);
CurrentRotation.Yaw = FMath::Lerp(CurrentRotation.Yaw, TargetYaw, .05f);
GetOwner()->SetActorRotation(CurrentRotation);