Step 1

Preheat the oven to 375 degrees F (190 degrees C). Line a sheet pan with parchment paper or a silicone baking mat (such as Silpat®).

Step 2

Cut bread into 1/2-inch slices. Transfer onto the prepared sheet and brush very generously with melted butter until well soaked.

Step 3

Bake in the preheated oven until light golden brown, about 30 minutes. Remove from the oven and let cool before topping. Increase the oven temperature to 450 degrees F (230 degrees C).

Step 4

Add cream cheese, Gruyere, provolone, 1/4 cup Parmigiano-Reggiano, garlic, green onion, pepper, salt, cayenne, nutmeg, spinach, and artichokes to a mixing bowl and mix until thoroughly combined.

Step 5

Use a spoon to top each piece of toast with at least a 1/2-inch thick layer of the cheese, artichoke, and spinach mixture. Grate some extra Parmigiano-Reggiano on top of each toast if desired.

Step 6

Bake in the preheated oven until the tops and bottoms are nicely browned, about 25 minutes. Serve warm or at room temperature.