Stuffed Portobello Mushrooms with Spinach and Goat Cheese

From America’s Test Kitchen - can be a side or a veggie main dish. Watch them in the broiler - we lit them on fire the first time we made this! :)

ingredients

10 portobello mushrooms, stems removed (reserve for filling)
4 tbsp olive oil
table salt
2 6 oz bags baby spinach (10 cups)
2 tbsp water
2 large slices white bread, torn into quarters (or use panko)
2 tbsp unsalted butter
2 medium onions diced small (2 cups)
4 medium garlic cloves minced or pressed (4 tsp)
1/2 cups dry sherry
2 tbsp chopped fresh thyme leaves
4 oz goat cheese crumbled
1/4 cup heavy cream
1 cup walnuts toasted and roughly chopped
2 tsp juice from one lemon
ground black pepper

directions

1
Adjust oven rack to upper middle position place rimmed baking sheet on rack, and heat oven to 400 degrees. Using sharp knife, cut 1/4 inch slits spaced 1/2 inch apart in crosshatch pattern on surface of 8 mushrooms. Dice remaining 2 mushroom caps and reserved stems into 1/2 inch pieces; set aside (3 cups)
2
Brush both sides of caps with 2 tbsp oil and sprinkle evenly with 1 tsp salt. Carefully place caps, gill side up, on preheated baking sheet. Roast until mushrooms have released some of their juices and begin to brown around edges, 8 to 12 minutes. Flip caps over and continue to roast until liquid has completely evaporated and caps are golden brown, 8 - 12 minutes longer. Remove mushrooms from oven and heat broiler.
3
Meanwhile, place spinach and water in large microwave safe bowl. Cover bowl with large dinner plate. Microwave on high power until spinach is wilted and decreased in volume by half (up to four minutes). Using potholders, remove bowl from microwave and keep covered 1 minute. Carefully remove plate and transfer spinach to colander set in sink. Using back of rubber spatula, gently press spinach against colander to release excess liquid. Transfer spinach to cutting board and coarsely chop. Drain again.
4
Pulse bread in food processor until coarsely ground (or use panko). Heat 1 tbsp oil and 1 tbsp butter in 12 inch skillet over medium heat until butter is melted. Add bread crumbs and 1/2 tsp salt; cook, stirring frequently until light golden brown, 5-8 minutes. Transfer crumbs to small bowl and wipe out skilled with paper towels.
5
Return now empty skillet to medium high heat, add remaining tbsp oil and heat until smoking. Add chopped mushrooms and cook without stirring for 2 minutes. Continue cooking, stirring occasionally, until lightly browned, 4-6 minutes longer. Transfer to medium bowl.
6
Add remaining tablespoon butter and onions to skillet; cook, stirring occasionally until onions are light brown 5 to 6 minutes. Add garlic and cook until fragrant about 30 seconds. Stir in sherry and cook until almost no liquid remains, 1 to 2 minutes. Remove pan from heat, stir in lemon juice and season with salt and pepper to taste.
7
Flip caps, gill side up and distribute filling evenly among mushroom caps; top each with 2 tbsp of bread crumb mix. Broil mushrooms until crumbs are golden brown 1 to 3 minutes. Serve immediately.