How can I write shell output if shell script is generated by batch

I have a Docker container myContainer and two simple batch scripts:

• generateShell.bat

@echo off 
echo #!/bin/bash > helloworld.sh
echo ...>> helloworld.sh

• runShell.bat

@echo off 
call generateShell.bat
docker exec -i myContainer bash < helloworld.sh

When I run runShell.bat, helloworld.sh runs in Docker container. I want to generate something in helloworld.sh so that writes output to .txt file in container. I tried

echo echo Hello World > output.txt>> helloworld.sh

but in that case I get only

Hello World

in Windows command prompt and no generated .txt files neither in container nor on host.