1. It might have been baking for too long.
2. fat-flour ratio is off
3. eggs were too cold
To avoid this, keep a check on the cake. 10 min before the stipulated time in the recipe, insert the skewer and check.
If there are only few crumbs that stick to the skewer, reduce the heat by 20 degrees and let it bake.
Or you may even turn off the oven and let the cake cook in the residue heat.
A more handy option is to always wrap a wet towel strip around the cake mould. This will not only ensure a flat surface on the cake top, but also un-cracked surface.
