Preheat oven to 375°F (190°C).
In a medium skillet, heat olive oil over medium heat. Add minced garlic and sauté for 1 minute until fragrant.
Add chopped spinach to the skillet and cook for 2-3 minutes until wilted. Remove from heat and set aside.
In a large bowl, combine ricotta cheese, egg, Parmesan cheese, sautéed spinach with garlic, dried Italian seasoning, salt, and black pepper. Mix well.
In a 9×13 inch baking dish, spread 1/2 cup of low-carb marinara sauce evenly on the bottom.
Layer 1 cup of shredded chicken over the sauce.
Spread half of the ricotta and spinach mixture over the chicken layer.
Sprinkle 2/3 cup of shredded mozzarella cheese over the ricotta layer.
Repeat the layering: spread 1/2 cup marinara sauce, 1 cup shredded chicken, the remaining ricotta mixture, and then 2/3 cup mozzarella cheese.
Top the lasagna with the remaining 2/3 cup shredded mozzarella cheese.
Cover the dish tightly with aluminum foil.
To make ahead: Refrigerate the covered dish for up to 2 days before baking.
When ready to bake, remove the foil and bake uncovered for 25 minutes.
Replace the foil and bake an additional 15 minutes.
Remove foil and bake for 5 more minutes until the cheese is golden and bubbly.
Let the lasagna rest for 10 minutes before slicing and serving.