Caramelized Onion & Gruyere Macaroni and Cheese

There is a new Belgium style bar/restaurant that opened not too long ago nearby, and I couldn't wait to try it.  A few weeks ago, we decided to give it a try for dinner, especially since we had a coupon.  Though their food menu is quite small, the food itself is delicious.  We started by sharing some awesome poutine (which I'll have to try to make some night) to go with our beer (which we ordered from their insanely large beer menu).  For our entrees, Joel ordered a short rib sandwich and I got their "mac & cheese of the day" which happened to be caramelized onion and bacon mac and cheese.  I knew I had to recreate it at home, so I started to look at the many different mac and cheese recipes that I had bookmarked over the past year or so.  This one from Daily Unadventures of Cooking seemed to be the closest to what I was looking for.

1 tablespoon Olive Oil
1 Onion
1 tablespoon Butter
1 1/4 cups Milk
3 cups Dried Pasta
Up to 1/2 cup Reserved Pasta Water (I forgot this and I drained the whole thing, but it didn't matter)
1/2 cup Gruyere Cheese, shredded
3-4 pieces Thick-Cut Bacon, cooked and chopped (I added)
4 tablespoons Panko Bread Crumbs (I added)

Cut the onion in half and then cut each half into thin slices.  Heat a large saucepan over medium heat.  Add the onions and salt.  Saute the onions until they become deep brown and caramelized.  Add the butter and stir to melt.  Once melted, stir in the flour and cook, stirring for 3 minutes.  Slowly add the milk, stirring to incorporate.  Once the milk has been added, add the bay leaf and let the mixture gently simmer for 10 minutes, stirring regularly so that it does not burn.  Season to taste with salt and pepper.  Meanwhile, cook the pasta, according to package directions, until al dente.  Drain and reserve 2 cups of pasta water.  Stir the cheese into the sauce.  Add the pasta and stir in just enough pasta water to coat all of the pasta with the sauce.  Add the bacon and mix to incorporate.  Transfer the pasta to a casserole dish or 4 individual ramekins.  Sprinkle with remaining cheese and bread crumbs.  Broil until the top of the pasta is bubbly and brown.