Whenever I've cooked quiche, it's been in a round tin of around 10-12 cm diameter. I've used 5-6 eggs along with other ingredients like chicken and vegetables.  After it comes out of the oven, I find that the height is low (around 2cm) when I thought/expected it to be higher.   I find it hard to know when it's actually 'cooked' as the egg parts are runny when it's in the oven, only solidifying when I take it out.   How can I tell that the quiche is done? 
 Butter in liquid state is more easy to mix and get an homogeneous batter. Given enough effort, creamed butter does the same thing.   By effort, I mean making sure not to overlook tiny lumps of heterogeneous batter; otherwise the texture will be different. Also, if you are mixing the eggs with some lukewarm butter, it may be a health concern if you don't use the batter right away.  If you had a crumbly cookie-like texture, then my first thought is that the ratio was not correct or something was missing. 