Red onion and mature cheddar tart

A friend of mine makes a red onion tart, and while I've never had it, in fact I've never even seen it, but it always sounds so good when she tells me about it.  So, today, on a whim (and because red onions were 49 cents / lb this week) I decided that was going to be dinner.

After a quick google search I found this lovely gent advertising Collier's mature cheddar with a red onion tart recipe.  I did have to tweak the recipe a little to use the contents of my fridge rather than run to the store, but it was heavenly.  I had no cream so I used 1% milk, and added in an extra egg for good luck.  I had no rosemary so decided thyme would do....and it did.  (I used jarred roasted garlic and again it was still fabulous).

No idea why this rotated itself when I uploaded.....