Heat oil in a heavy bottomed sauce pan over medium heat and add flour. Cook, whisking occasionally, until the flour just starts to change color and turn fragrant, about five minutes. Do not let the flour brown.

Add the garlic and cook until very fragrant, about 30 seconds longer.

Combine milk and half and half in a measuring cup and add about a 1/2 cup at a time to the flour mixture, whisking after each addition until smooth. Reduce heat to medium-low and bring to a simmer, stirring constantly. Add the Gruyere, Parmesan, salt, pepper, and nutmeg. Stir until the cheese has just melted, then remove from the heat and set aside.

Working over a bowl or the sink, squeeze the liquid out of the spinach. Chop the artichokes fine and then fold both the spinach and the artichokes into the sauce.

Pour the sauce into an oven safe baking dish (or multiple dishes) or a hollowed out bread bowl. Top with the shredded mozzarella.

Bake in a preheated 375 degree F oven for about 30 minutes until the edges are bubbly and the cheese on the top is dark golden brown. Serve with bread cubes or chips.