Melt 1/2 cup of unsalted butter in a skillet over medium heat. Sauté a finely chopped medium onion for 4-5 minutes until translucent.

Add 1 pound of chopped cremini mushrooms and 2 minced garlic cloves. Cook for about 5 minutes until moisture is released.

Pour in 1/3 cup of dry sherry, 1 teaspoon of salt, and 1/4 teaspoon of black pepper. Cook for another 10 minutes, stirring frequently.

Preheat your oven to 350°F (175°C). Prepare a mixing bowl for the next step.

In a large mixing bowl, combine 8 ounces of room temperature cream cheese and 3 eggs. Mix until smooth.

Stir in 2 cups of chopped spinach and 1 1/4 cups of chopped walnuts to the creamy mixture.

Fold in the cooled mushroom mixture until everything is well combined.

Transfer the mixture into a buttered loaf pan and cover with aluminum foil.

Place the loaf pan into a larger dish filled halfway with hot water and bake for 1 hour and 15 minutes.

Cool the pâté at room temperature before chilling in the refrigerator until firm.