I found this question while attempting to find an answer myself. The two existing answers ignored parts of the original question. This question is very similar to this other question, but with the explicitly stated requirement that the code within the method blocks should not be folded.
The other question has a better answer:
Code -> Folding -> Expand all to level -> 1
The naming on this is a little weird because it says "Expand" when you're really trying to collapse all method bodies. But if the method bodies are already expanded, this will collapse them. The shortcut for this is ctrlshiftNumPad *, 1. If you find that shortcut combination cumbersome or don't have a num pad, you can create your own shortcut by going to Preferences -> Keymap
.
This seems to me like the perfect solution. It won't expand or collapse any blocks at other levels. So if you manually collapse a block within a method body, this will leave it collapsed.
If that's not your preference, and you want it to expand all blocks within the method bodies while collapsing the method bodies themselves, you could create a macro that runs Code -> Folding -> Expand All
followed by Code -> Folding -> Expand all to level -> 1
, and then map your keyboard shortcut to that macro.