So, I made the almond cake again today following BDL's guidelines :
Don't over beat the batter
Lower oven temperature from 350 to 300 degrees (convection bake)
When I mixed the almond paste into the creamed butter & sugar the speed was too low to break it up thoroughly so there were little bits in the batter. It didn't seem to affect the final product but I'd prefer it to blend a bit better.
The cake rose as before but when it settled it did...