Kanye West just got official approval to start building a new monster of a home on his ranch in Wyoming (the lakeside one) -- and by the sound of it, he's got a lot of work to do.

filed in Cody, Wyoming, which were just signed off on over the past couple months.

Like we said, Ye's paperwork says he plans to build a single-family residence -- the primary one he'll use for him, Kim and the kids -- which will replace the set of lakeside cabins and dwellings currently there.

Speaking of massive square footage, he also filed docs seeking permission to build TWO underground garages at 10,000 sq.