Mathematical Methods for Physics is such a great course. Took the course, and an Advanced version in undergraduate when I was still attempting to be a physicist. The course is at its core a bunch of very important Mathematical concepts that a Physicist or adjacent will need that you won't quite ever come across naturally in mathematics courses unless you go into graduate studies. A "Here is the problem, here is the math and here is why" is just very useful. Legendre Polynomials, Bessel Functions, Lagrangian, Fourier Functions. Just tons of interesting and really useful math that when you hit a problem in their space you have a super power.<p>My professor for the courses always said it was about putting more mathematical tools in your tool box. Which is a perspective I've since carried.