I understood from a 90-something year old friend of my grandmother, that the collapsing is due to over-beating the eggwhites before the sugar starts to go in. They should be just barely stiff, soft peaks, rather than hard peaks.
Then add the sugar slowly, spoonful at a time, so that each spoonful is dissolved before the next goes in (this extra beating brings it up to 'hard peak' stage.) Making sure all of the sugar dissolves properly stops that stickly, toffee-ish bubble stuff on the sides and bottom.
So as far as she believes (and she is know to our family as an expert sweets, biscuit and dessert cook) it's to do with the techniques, not the recipe, which is why different people get different results with the same recipe.
HTH
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