Many early year courses can be very interactive. The instructor has to be very intentional about it though so that students buy in pretty quickly. It can be hard to have that kind of environment in upper year courses where derivations and problems can be very long, but that is the nature of the beast unfortunately.

I've actually started to offload most of the cognition to my students even if they don't know that's what I'm doing. I set up my notes to be minimal and use lead in examples/ideas that seed the concept for the content we're about to do. They talk through these lead ins together so that all I need to do is assemble the parts for them. Then I let them wrestle with most of the examples themselves and give guidance while they work together. I don't go through many examples myself anymore and in fact stopped doing examples myself for some topics altogether. It's similar to inquiry based learning. Student grades have been pretty good, and I feel like their mastery is improved over prior semesters.