My First Barefoot Failure

So let me start off by saying I LOVE Barefoot Contessa.  Ina Garten is an amazing woman.  I seriously wish that I lived in the Hamptons, in her house, with her garden (!!!).  I have my DVR set up to record all of her shows on the Food Network - no lie.
Now that I've reinforced the fact that I'm a major fan, I have to say that I recently tried one of her recipes, and was not a fan of it.  I usually bookmark her recipes after I watch them on tv, but this one looked so good I decided I had to make it.  I figured - zucchini, onions, creamy milk and cheese with a crusty top - how bad can that be?  (one of Ina's favorite phrases)
I think that maybe gratins should be saved just for potatoes.  At the very least, the onions should have been eliminated.  A lot of people that reviewed the recipe said to decrease the onions - I think they just shouldn't be there.  Maybe it was just me?  Also, I didn't use Gruyere.  I had just bought some Raclette cheese from Cville Market - it was advertised as being a great gratin cheese.  I think it definitely needs something stronger.
I'm not telling you to not make this recipe.  Just giving my honest opinion.  Definitely check out the reviews before making it.

Recipe: Zucchini Gratin (from Barefoot Contessa)
Ingredients:
6 tbsp unsalted butter, plus extra for topping
1 lb yellow onions, cut in 1/2 and sliced (3 large)
2 lbs zucchini, sliced 1/4-inch thick (4 zucchini)
2 tsp kosher salt
1 tsp freshly ground black pepper
1/4 tsp ground nutmeg
2 tbsp all-purpose flour
1 cup hot milk
3/4 cup fresh bread crumbs (I used panko)
3/4 cup grated gruyere (I used raclette)

Directions:
Preheat the oven to 400 F.
Melt the butter in a very large (12-inch) saute pan and cook the onions over low heat for 20 minutes, or until tender but not browned.  Add the zucchini and cook, covered, for 10 minutes, or until tender.  Add the salt, pepper, and nutmeg and cook uncovered for 5 more minutes.  Stir in the flour.  Add the hot milk and cook over low heat for a few minutes, until it makes a sauce.  Pour the mixture into an 8x10-inch baking dish.

Combine the bread crumbs and Gruyere and sprinkle on top of the zucchini mixture.  Dot with 1 tbsp of butter cut into small bits and bake for 20 minutes, or until bubbly and browned.