Preheat the oven to 350°F and coat a 9x13 oven-proof casserole dish with oil spray

Add the oil to a large pot set over medium heat and when it is hot add the farro berries, stirring to coat with the oil. Cook the farro, stirring frequently until they become toasty. You will hear them pop and crackle as they toast. Pour 6 cups of water over the farro and bring to a boil. Cook the farro until it al-dente or still has a little bite. It should take 15 to 30 minutes depending on the type of farro you have.

Drain the farro and transfer it to the prepared casserole dish, spreading evenly across the bottom of the dish.

Add the sliced mushrooms on top of the toasted farro in an even layer.

To the same skillet, add the sliced leeks and the garlic and cook until the leeks become wilted and the garlic is fragrant. Transfer to the casserole and spread evenly on top of the mushrooms. Distribute the drained sun-dried tomatoes over the leeks. In a dish or pitcher, whisk the chicken broth and sour cream together and pour over the casserole. 

Sprinkle the shredded cheese over the top and add the chicken thigh, skin side up. Season with salt and pepper and dust lightly with paprika.

Transfer the baking dish to the middle rack of the oven and bake for 45-50 minutes until the chicken thighs reach an internal temperature of 165°F. Remove from the oven and serve immediately.