Increase time by 15 minutes by 4 rows per ‘time slot’

I’m trying to create a list of certain times for people to sign up in a form.

I did the following by hand, but I’d like to use a formula for it. Looked over the internet for iteration formulas for time but no success, so that’s why I ask here.

This is my sheet now :

https://i.imgur.com/6U1WucC.png

As you can see there are 4 time slots for every time available (4 rows from 12:30, 4 rows from 12:45)

I have to extend these time slots till 18:00.

Someone knows how to do this by formula since it’s really time consuming to do this by hand.

This should be the output:

06.01.2022 12:30

06.01.2022 12:45

06.01.2022 13:00

And so on. Till 18:00.

Any help is highly appreciated!