Here are a list of non superficial online courses that I truly feel are equivalent to upper division undergraduate or graduate level difficulty, off the top of my head, most of these taught by some of the best professors you could possibly find to teach the topic:
Probability Theory: https://www.edx.org/course/probability-the-science-of-uncertainty-and-data
Optimization: https://lagunita.stanford.edu/courses/Engineering/CVX101/Winter2014/
AI overview (e.g reviews algorithms and presents some introductory overview of the field): http://ai.berkeley.edu
Machine Learning: https://www.edx.org/course/machine-learning-columbiax-csmm-102x-0
PGMs: https://www.coursera.org/specializations/probabilistic-graphical-models
Deep RL: http://rail.eecs.berkeley.edu/deeprlcourse/
Robotics (Perception/Navigation or topics relevant to CS): https://www.edx.org/course/autonomous-mobile-robots
Cryptography: https://www.coursera.org/learn/crypto
Compilers: https://lagunita.stanford.edu/courses/Engineering/Compilers/Fall2014/about
Graphics: https://www.edx.org/course/computer-graphics-uc-san-diegox-cse167x-3
There is also a ton of material you can find just by googling e.g. "berkeley 184" or "cmu 10708" but they aren't technically moocs.