Spinach-Artichoke French Bread Pizza

1 baguette, quartered
2 T butter
2 T extra-virgin olive oil
1 onion, finely chopped
3 cloves garlic, finely chopped
Salt and pepper
3 T flour
1 1/2 C milk
1 pinch nutmeg
Two 10-ox. boxes frozen spinach, thawed and squeezed dry
One 9-ox. box frozen artichoke hearts, thawed
1/2 C grated parmigiano-reggiano cheese
2 C shredded mozzarella or provolone cheese
2 T finely chopped fresh thyme

1. Preheat oven to 400F. Arrange the bread on a baking sheet. In a medium skillet, melt the butter with the oil, 2 turns of the pan, over medium heat. Add the onion and garlic and cook until softened, about 5 minutes; season with salt and pepper. Whisk in the flour for 1 minute, then whisk in the milk and season with the nutmeg. Cook until thickened, about 5 minutes.
2. Pull the spinach apart, then add to the sauce. Fold in the artichokes and cook until heated through. Stir in the parmigiano-reggiano, season with salt and remove from heat.
3. Spread the spinach and artichoke mixture on the bread and top with the mozzarella. Bake until the cheese is melted, 10-12 minutes. Top with the thyme.