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

Manipal, Karnataka

Anna University

IIST, Thiruvananthapuram

Madras Institute of Technology,Chennai

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

Colleges offer Aeronautical Engineering

Good Luck!!!!