It was deliberate! I prebaked the shell, leaning the pastry onto a cone-shaped cardboard form. Then after it was baked, I cut the cardboard out. Unfortunately, it wasn't really baked hard enough, and the side that you see that's collapsed, collapsed. Then I poured in the filling and reheated the pie to warm it up. Then I made the decorative lava flows :-)

Yeah, I think I thought it was Krakatoa too. Live and learn!