Preheat oven to 375.
In large skillet, melt 2 tablespoons of butter. Season chicken breast and add to butter in batches adding another 2 tablespoons in between. Brown chicken for 5 minutes, turn and brown the second side for 1-2 minutes. Remove to a plate and keep warm.
Heat ½ teaspoon of olive oil in the same skillet. Add sliced mushrooms and cook until slightly soft.
Meanwhile, heat a large stockpot, melt ½ teaspoon of olive oil. Add shallots and garlic to the oil, stirring constantly for 1 minute. Add orzo. Stir and cook until orzo is lightly toasted and fragrant. Season orzo with sage and salt.
Pour orzo into a 13 x 9 baking dish. Top with chicken breast and mushrooms. Pour chicken stock over orzo and chicken. Bake for 45-50 minutes or until chicken reaches 165 degrees and liquid has been absorbed, stirring occasionally.
