Start by washing the rice and soak in water for 15 minutes.
Preheat the oven to 350F.
Meanwhile in a pan over medium heat, melt 1 Tablespoon of butter and brown the chicken tenders, 2-3 minutes each side, season with some salt and pepper, set aside.
Drain the rice, add salt, pepper, sour cream, Mascarpone cheese and the remaining 1 Tablespoon of butter, mixing all very well until all rice is covered well.
In a deep oven dish, authentically a clay one, add about 5 Tablespoons of the rice mixture to cover the bottom and spread evenly.
Add the chicken pieces if using, then cover with the remaining rice, level the surface.
In a pot over medium heat, add the milk along with the broth and bring to a boil, turn off the heat and season with a dash of black pepper.
Add the hot liquids to the rice , place the dish into a bigger oven dish or pan filled halfway with water.
Bake in the oven for almost an hour until the rice is fully cooked and the surface turns golden brown.
Let it cool down and serve.