Preheat oven to 350°F.
Grease a muffin tin with non-stick spray. Press one slice of bread into a muffin well (does not have to perfectly). Repeat for each portion you're making.
Whisk the eggs, cream, parmesan, salt, and pepper together in a bowl.
Place a pinch of mozzarella cheese at the bottom of each bread mold.
Heat the oil in a non-stick pan over medium heat. Sauté the onion and garlic for 2-3 minutes, add the spinach and sauté until wilted, then remove from the heat. Season with salt and pepper to taste. Drain as much liquid from the spinach as you can.
Mix in the artichokes and equally distriubute the mixture in the bread.
Pour the egg mixture over the spinach-artichoke mixture. Top with remaining mozzarella.
Place in the oven for 30-35 minutes, until crust is golden brown.
Let sit for 3 minutes then gently remove the popovers from the muffin tin and serve.