The best way?
For years, I did not even think it possible one could easily repair their own dash pads. I have read some threads (perhaps use the search function to locate) on this site where people have made repairs to their own dash pads. The repairs look good, but more time must pass to know if the repairs continue to look good, and how well they withstand exposure to sunlight. While they have had some levels of success, it confirmed it's a good deal of work.
For me, one who can DIY nearly anything on my classic car, the best way is sending it out to a restoration service provider and having the whole thing redone, so it looks new again.
Your dash pad, believe it or not, is in pretty good shape. The ones I have on hand are much worse. The are not only cracked in multiple places, but some of those cracks are wide, like a tiny Grand Canyon, and show uplift near the edged of the cracks. Yes, the dash pad material curves upward making a more pronounced and ugly crack.
I would trade any of them for your nicer looking one in a heartbeat.