Preheat oven to 375°F. Lightly coat a 9-by-13-inch baking dish with cooking spray.

Heat oil in a large pot over medium heat. Add chicken, sprinkle with salt and pepper and cook, stirring, until opaque on all sides, about 4 minutes. Add garlic and cook, stirring, for 1 minute. Add artichoke hearts and broth; cook, stirring, until the liquid is reduced and the chicken is cooked through, 3 to 4 minutes. Remove from heat and stir in cauliflower rice, spinach, yogurt and 1/2 cup mozzarella.

Transfer the mixture to the prepared baking dish and sprinkle the remaining 1/2 cup mozzarella over the top. Bake until the cheese is melted and starting to brown in spots, 20 to 25 minutes. Let rest for at least 5 minutes before serving.