All training for EASA licences and ratings must be conducted at an ATO and be approved. The syllabi and content for such courses are contained in the
AMC and GM to Part FCL
The ATO will write a Training Manual detailing the training they will give on their approved courses. Upset training is usually as agreed between the ATO and the sponsor.
If you wish to produce an extra curricular course that is not part of the licence or rating issue process then it would fall outside the approval process if the candidate is a qualified pilot.
MPL courses are only conducted at ATOs approved to conducted Integrated Training and would normally produce their own course material.