Not all NITs and IITs offer B.Tech in Aeronautical Engineering as few of them offers B.Tech in Aerospace as there is no such big difference in both the courses because both of them belong to the same parents.

 
Also, there are few colleges which offer this program as you can check their names below -

IIT-Bombay (Aerospace Engineering)

IIT-Madras  (Aerospace Engineering)

IIT-Kanpur  (Aerospace Engineering)

IIT- Kharagpur  (Aerospace Engineering)

SRM, Chennai (Aeronautical Engineering)

Manipal, Karnataka (Aeronautical Engineering)

Anna University (Aeronautical Engineering)

IIST, Thiruvananthapuram (Aeronautical Engineering)

Madras Institute of Technology,Chennai (Aeronautical Engineering)

To check the complete list, you can go through the below link -

Colleges offer Aeronautical Engineering

 

Good Luck!!!!