Question: Who composed a form of song in the Carnatic music repertoire in all the '72 Melakarta Ragas?

Context paragraphs:
Kosalam: Kosalam (pronounced kōsalam) is a rāgam in Carnatic music (musical scale of South Indian classical music).  It is the 71st "Melakarta" rāgam in the 72 "melakarta" rāgam system of Carnatic music and is the "prati madhyamam" equivalent of "Shoolini", which is the 35th "melakarta".  It is called Kusumākaram in Muthuswami Dikshitar school of Carnatic music.

List of Janya ragas: Janya ragas are Carnatic music ragas derived from the fundamental set of 72 ragas called "Melakarta" ragas, by the permutation and combination of the various ascending and descending notes.  The process of deriving janya ragas from the parent "melakartas" is complex and leads to an open mathematical possibility of around thirty thousand ragas.  Though limited by the necessity of the existence of individual "swaroopas" (unique identities) for the "janya" ragas, a list is never comprehensive or exhaustive.  Thus the list below is open to additions or corrections.  Moreover, some musicians experiment and use new scales, leading to new "janya" ragas.  The 72 "Melakarta" ragas are numbered according to the ancient Indian system for numerical notation — the "Katapayadi system".

Prashanth Iyengar: Prashanth Iyengar (born 12 January 1973) is a classical musician and veena exponent from India, in the Carnatic Music genre.  He is a performer, composer and teacher.  He is the first composer from Karnataka to have composed Varnams in all the '72 Melakarta Ragas.  He holds the Limca national record for his marathon veena concert spanning 24 hours at Srirangapatna Temple in the year 2011.

Simhendramadhyamam: Simhendramadhyamam or Simmendramadhyamam is a rāgam in Carnatic music (musical scale of South Indian classical music).  It is the 57th "melakarta" rāgam in the 72 "melakarta" rāgam system of Carnatic music.  It is called Sumadyuti in Muthuswami Dikshitar school of Carnatic music.  It is said to be borrowed into Hindustani music from Carnatic music.

Melakarta: Mēḷakarta is a collection of fundamental ragas (musical scales) in Carnatic music (South Indian classical music).  "Mēḷakarta" ragas are parent ragas (hence known as "janaka" ragas) from which other ragas may be generated.  A "melakarta" raga is sometimes referred as "mela", "karta" or "sampurna" as well, though the latter term is inaccurate, as a "sampurna" raga need not be a "melakarta" (take the raga "Bhairavi," for example).

Varnam: Varṇam is a form of song in the Carnatic music repertoire consisting of short metric pieces which encapsulate the main features and requirements of a "raga".  The features and rules of the raga (also known as the "sanchaaraas" of a raga) include how each note of the raga should be stressed, the scale of the raga, and so on.

Jana Ranjani: Jana Ranjani is a raga in Carnatic music, classical music of South India.  It is a "janya" raga of Shankarabharanam, 29th in the 72 Melakarta ragas.  The Raga is named thus because it induces a feeling of enjoyment ("Jana" - People and "Ranjani" - can be enjoyed by people) among the "rasikas"(audience).

Shanmukhapriya: Shanmukhapriya is a rāgam in Carnatic music (musical scale of South Indian classical music).  It is the 56th "melakarta" rāgam (parent scale) in the 72 "melakarta" rāgam system of Carnatic music.  It is called Chāmaram in Muthuswami Dikshitar school of Carnatic music.  It is said to be borrowed into Hindustani music from Carnatic music.

Poornachandrika: Poornachandrika is a raga in Carnatic music, classical music of South India.  It is a "janya" raga of Shankarabharanam, 29th in the 72 Melakarta ragas.

Dhenuka (raga): Dhenuka (pronounced dhēnukā) is a rāgam (musical scale) in Carnatic music.  It is the 9th Melakarta rāgam in the 72 melakarta rāgam system of Carnatic music.

Supporting paragraphs: Prashanth Iyengar Varnam
Answer: Prashanth Iyengar