In a large skillet, melt 2 tablespoons of unsalted butter over medium heat. Add 1 medium onion, finely chopped, and sauté for about 4-5 minutes until it turns translucent and fragrant.

Add 8 ounces of finely chopped cremini mushrooms and 2 cloves of minced garlic to the skillet. Cook for an additional 5 minutes, stirring frequently.

Pour in 1/4 cup of dry sherry along with 1/2 teaspoon of salt and 1/4 teaspoon of freshly cracked black pepper. Cook for about 10 minutes until the mushrooms are fully tender.

While the mushroom mixture cools, preheat your oven to 350°F (175°C) and prepare a loaf pan.

In a mixing bowl, combine 8 ounces of cream cheese, 2 beaten eggs, 1 cup of chopped spinach, and 1/2 cup of finely chopped walnuts. Mix well.

Gently fold the cooled mushroom mixture into the cream cheese blend until evenly combined.

Carefully pour the mixture into the prepared loaf pan, smoothing the top.

Place your loaf pan in a larger baking dish filled with boiling water and bake in the preheated oven for 1 hour and 15 minutes.

Let it cool for at least 30 minutes at room temperature before placing it in the refrigerator.