Portabello mushroom lasagna

Had plans to make this lasagna for my bosses, who have a tiny (and very precious) new baby boy at home to take care of.  Or course, I ended up making two because someone at home wanted to eat lasagna, too. :-)
I started with Ina Garten's recipe for portabello mushroom lasagna, but tweaked it in the following ways:

1. I added more veggies: leeks, spinach, and garlic (never use frozen spinach in lasagna, always microwaved fresh - frozen is too tough, strong-tasting, and wet).

2. I added a second type of cheese: mozzarella (for this dish I recommend sticking to just parmesan because the dish relies on the stronger, salty flavor of parm - I just bought moz on accident because I originally was making a tomato sauce lasagna).

3. I added thyme to the mushrooms and leeks as well as a splash of balsamic vinegar at the end of sauteeing because I thought they needed all the flavor boost they could get, this being a béchamel lasagna.

Turned out pretty well but I'm partial to tomato-based lasagnas!