Preheat your oven to 375 degrees Fahrenheit (190 degrees Celsius) and grease a 9x13 inch baking dish.
In a large mixing bowl, whisk together the softened cream cheese, sour cream, salsa, green chiles, and taco seasoning until the mixture is smooth.
Stir in the riced cauliflower and the cooked shredded chicken, ensuring all pieces are thoroughly coated in the cream sauce.
Fold in 1 cup of the shredded Mexican cheese blend into the chicken mixture.
Spread the mixture evenly into the prepared baking dish using a spatula.
Sprinkle the remaining 1 cup of shredded cheese over the top and arrange the jalapeño slices across the surface.
Bake for 25 to 30 minutes until the casserole is bubbling and the cheese on top has melted and begun to brown slightly.
Remove from the oven and let stand for 5 minutes before garnishing with fresh cilantro and serving.