Remember when everyone was cutting their maple trees flat on top? My uncle did that, said it looked tidy. Whole thing grew back weird dense twigs that iced over and smashed his shed roof. @the_michael is right about guiding the shape early.

Wait, loose fill insulation? That stuff is the absolute worst to get out of anything. How did the cat even manage to dive that deep into it? Honestly, that's a whole different level of mess to clean up.