This was my first experiment with the official spice blend of Maryland...Old Bay. While it's not strictly necessary to the dish, it certainly helps add to the nautical feel of the "boats"! If you don't like or can't procure some Old Bay, it could easily be swapped out for an equal amount of herbes de Provence, tarragon and oregano, cayenne and sage, or any other combination you fancy. —EmMa
In a large frying pan, heat the olive oil on medium heat. Meanwhile, slice the onions thinly; add the garlic and onions to the pan and cook until the onions are significantly softened, 8-10 minutes.
While the onions are cooking down, wash and dry the spinach. When the onions are soft, add the spinach, salt, and pepper. Cook until the spinach is fully wilted, 3-5 minutes.
Make the chicken boats: slice into each breast with a large knife as though you were going to open the breast up like a book (you will in a moment). Stop halfway through the breast; using the tip of the knife, cut deeper into the middle of the breast, making sure the ends remain only half-fileted. Pull the cut edges open into the boat shape and place opening-down in a large baking dish. Sprinkle liberally with salt, pepper, oregano, and Old Bay. Flip over again. Preheat oven to 400˚ F (205˚ C).
Once the spinach is wilted, remove pan from heat and crumble goat cheese into the pan. Mix until the contents have coalesced. N.B.: It's better to have to add more goat cheese than to have too much, so you may want to crumble it into the pan in batches, mixing in between to achieve the right ratio.
Spoon the mixture into the chicken boats; you'll probably have a fair amount of extra, don't be afraid to pile it on the breasts. Top with panko and a dusting of Old Bay. Add the chicken broth to the baking dish (don't pour it directly on the chicken, you don't want soggy panko!) and put into the oven for 40 minutes, covered with aluminum foil.
Check the temperature with a meat thermometer; if it's sufficiently high, remove the foil and cook for another 5-10 minutes. Serve hot with a crisp salad and potatoes au gratin.