Stuffed Portobello Mushrooms

I'm beginning to sound like a broken record. It seems I get all my recipe from three places, All Recipes, Food Network (and their website), and Cook's Illustrated/America's Test Kitchen.
This is no exception. For Thanksgiving, I was in charge of an appetizer. I've done stuffed mushrooms before, and the version printed in Number 95 looked delish. Fine it's been a long time since I've done stuffed mushrooms, but come on, they're mushrooms, with stuffing. I learned some tough lessons though by not following directions exactly. Learn with me people. . . .

Stuffed Portobello Mushrooms with Spinach and Goat Cheese
(the filling can be made in advance and kept in the fridge; just reheat it before stuffing the mushrooms)

10 small portobello mushrooms - Remove stems and chop. Also chop up two of the 10 mushrooms, so you're left with 8 to stuff and about 3 c of chopped mushrooms.
4 tbsp olive oil
salt
2 6 oz bags of baby spinach
bread for bread crumbs - I used some stale sourdough baguette I had around; use whatever you have (although the recipe calls for two slices of white sandwich bread, torn into quarters if you must know; you just want to end up with 1 1/2 c)
1-2 tbsp unsalted butter
2 medium onions, finely diced (approx 2 cups)
4 medium sized cloves of garlic (squish through a garlic press)
1/2 c dry sherry (I used Dry Sack)
2 tbsp chopped fresh thyme
4-5 oz goat cheese, crumbled
1/4 c ff half and half (recipe calls for heavy cream)
1 c walnuts, toasted (I used the Diamond walnuts that came already chopped to save myself some work)
2 tsp lemon juice
ground black pepper

And now for the million steps. . . * cracks knuckles before proceeding *
Place spinach and 2 tbsp of water in a microwave safe bowl with a cover and nuke for 3 minutes (I had to do this in two batches, and just divided the water). Spinach should be wilted and half of what it was before. Keep covered for a minute before moving spinach to a colander. Once I had nuked both batches, I let the spinach sit in the colander to drain and cool off while I did the rest. If you're impatient, use the back of a spoon or spatula to smoosh excess liquid out of the spinach. If you're patient and the spinach cools off, you can squeeze it by hand. You really want to get as much liquid out as possible. Roughly chop, smoosh or squeeze again, and set aside.
Pulse bread in food processor until coarsely ground.
Heat 1 tbsp oil (and 1 tbsp of butter if you'd like; I just used some butter flavored Pam to impart a buttery flavor to my oil) over medium high until warm. Add bread crumbs, 1/4 tsp salt and cook, stirring frequently until lightly browned, 5-8 minutes. Transfer to a bowl and wipe out skillet with a paper towel.
Add remaining tbsp oil back to pan and head over medium high until smoking. Add mushrooms to pan and let sit without stirring for 2 minutes. Continue cooking, stirring occasionally until lightly browned, 4-6 minutes. Transfer to a bowl.
Add 1 tbsp butter and onions to skillet (I probably could've gotten away with more Pam here, but decided to go for the real deal) along with the onions. Cook 5-6 minutes until onions are light brown. Add garlic and cook til fragrant, only 30 seconds or so. Stir in sherry and cook til almost no liquid remains, just a couple of minutes. Reduce heat to low and stir in the mushrooms, spinach, thyme, goat cheese, half and half (or cream), and walnuts. Cook until cheese is melted and veggies are well coated. Remove from heat and stir in the lemon juice and salt and pepper to taste.

As for the mushrooms, preheat oven to 400; preheat baking sheet on center rake as well. Using a sharp knife, cut a crosshatch of shallow slits (about 1/4 inch deep) onto the top of the mushroom (not the gill side) about 1/2 inch apart.
Brush both sides of caps with remaining 2 tbsp olive oil and sprinkle with salt. Place mushrooms, gill side up onto preheated baking sheet. Roast until mushies have released some of their juices and have begun to brown around the edges, 10 minutes or so. Flip over and roast for another 10 minutes until juices have evaporated and caps are golden brown. Mine remained soggy and messy the entire time which was unfortunate. Remove mushies and preheat the broiler.

If you made the filling in advance, now is the time to reheat it. It doesn't have to be piping hot, but it should certainly be warm. Fill caps, top with bread crumbs and broil for a few minutes. Do NOT walk away from the oven at this point! Just hang out and watch to make sure you don't burn the tops. Serve immediately.

Again, be sure to get the small ones if you're doing this as an appetizer; if you get the big ones you'll end up with a big delicious flaccid mess. Look for the ones that are 4 inches across or so. If you use the large ones, these will still work as a knife and fork vegetarian meal, but not so much as an app. They're awesome so I highly recommend you make them.