Step 1

Preheat oven to 400 degrees F (200 degrees C).

Step 2

Melt butter in a saucepan over medium-low heat; stir in onions and pinch of salt. Cook, stirring occasionally, until onions are soft, about 5 minutes. Stir garlic into onions and remove from heat.

Step 3

Mix green onion mixture, spinach, artichoke hearts, cream cheese, Gruyere, Parmigiano-Reggiano, hot sauce, nutmeg, salt, and pepper in a large bowl until combined.

Step 4

Spoon artichoke mixture into two ramekins. Top each with shredded mozzarella cheese.

Step 5

Bake in the preheated oven until tops are golden brown and bubbling, about 25 minutes.