Which Buddhist Meditation is comparable to Transcendental Meditation? A friend of mine was practicing zazen for many years.   They started to get discourage with their practice and started to explore transcendental mediation.  Now, they claim their progress with TM is far better in a matter of weeks when compared to zazen.  I was wondering if there is an equivalent to TM in any of the Buddhist traditions?  If so, what are the basics and framework of the parallel type of meditation?
What is TM (Transcendental Meditation)

Being a Buddhist, I only have a cursory familiarity with TM, but here it is. A TM practitioner is instructed to sit regularly, at least 15 minutes every morning, or more. Meditation is presented as joyful, easy, resting activity that does not require much effort. Instead of suppressing thoughts or holding uninterrupted attention on breath etc., the practitioner is instructed to let their mind expand in its natural state. This is a state of open unfettered unperplexed awareness, like your mind on a day when you have enough time that you don't have to rush and can instead allow yourself to "gather your thoughts". As the mind expands, all kinds of memories and thoughts start bubbling up into scope. At this point the meditator is instructed to use their personal mantra, especially selected to match their personal predispositions (this part sounds like upaya to me). After reciting the mantra several times until the thoughts calm down, the TM meditator can stop using the mantra, and let their mind expand naturally. This combination of letting the mind expand while not letting it wander is said to be the core principle of TM. Two other unique elements are the joyful &amp; resting mood that the TM meditator learns to associate with meditation, and the use of mantra.

What Buddhist meditation is similar to TM

I'm not aware of any Buddhist meditation that would combine the same exact elements in the same way as TM. However, all elements of TM are found in Buddhist meditation techniques:


The joyful and resting mood is like in satipatthana, like in 2nd jhana.
Letting the mind expand in its natural state is like zazen, like Mahamudra meditation.
Coming back when thoughts arise is like the labeling ("thoughts!") technique in beginner's samatha meditation.
Using mantra is like in mantra meditation.


So to me, TM sounds like a peculiar combination of techniques usually associated with beginner's meditation (using the mantra, coming back from thoughts), with intermediate-level technique of generating the joyful mood, plus a technique that firmly belongs at advanced meditation levels -- letting the mind expand in its natural state.