Jack
I find that in order to get the characteristic holes in baguettes the shaped
loaves need to be overproofed (by normal loaf standards) and risen to at
least 2 1/2 times and preferably 3 times the original volume. And yes, it is
easy to really overdo it and get pancake loaves but you've got to give the
bread a chance to develop the typical baguette texture. Of course you'll be
hard pressed to get a loaf as holey as a french commercial baker with his
steam-injected hearth ovens running at over 280 C but you can get pretty
close. Are you dumping boiling water into a hot roasting pan on the base of
the oven just before putting the loaves in? The steam generated is important
in the expansion of the crumb. It also helps expansion (and therefore
holyness) if you spray water into the loaves' slashes just before they go
into the oven but the volume of the final proof is the most important factor.
The loaves should be treated gently in the transfer to the oven as they are
very fragile when proofed as much as they should be. If you've never used
parchment or bake-o-glide to proof loaves on you might consider it for future
bakes.
Hope this helps
John Wright
Yorkshire
England