Luis Serrano is a Colombian-American mathematician and machine-learning educator (formerly at Google, Apple, and Udacity), best known as the author of Grokking Machine Learning (Manning) — one of the most widely-recommended modern textbooks for picking up ML from a math-grounded but accessible angle.
His CourseFlix listing carries Grokking Machine Learning, Second Edition. Material is paid and aimed at engineers and analysts picking up modern ML through a clear, math-aware introduction rather than a black-box library tour.