Remove the stems from the mushrooms and set them aside. Place the mushroom caps on a baking sheet lined with parchment paper.
In a mixing bowl, combine the cooked and chopped spinach, cream cheese, minced garlic, grated Parmesan cheese, breadcrumbs, olive oil, salt, and black pepper. Mix well until all the ingredients are evenly incorporated.
Finely chop the mushroom stems that were set aside earlier. Add them to the spinach mixture and mix until combined.
Spoon the spinach mixture into each mushroom cap, filling them generously.
Bake the stuffed mushrooms in the preheated oven for 20-25 minutes or until the mushrooms are tender and the filling is golden brown.
Remove from the oven and let the mushrooms cool for a few minutes before serving.
Notes
Choosing the right mushrooms — Opt for large white mushrooms with sturdy caps that can hold the filling without collapsing during baking. Cremini or portobello mushrooms can also be used for a more robust flavor.
Removing excess moisture — After cooking and chopping the spinach, make sure to squeeze out any excess moisture. This will prevent the filling from becoming watery and ensure a creamy consistency.
Seasoning the filling — Taste the spinach filling before stuffing the mushrooms and adjust the seasoning according to your preference. Add more salt, pepper, or garlic if desired.
Garnishing with fresh herbs — Before serving, sprinkle some freshly chopped herbs such as parsley or chives on top of the stuffed mushrooms. The herbs will add a pop of color and freshness to the dish.