Preheat the oven to 350 degrees. In a small saucepan, melt the butter over a low flame. Add the oil and rosemary and stir until combined. Remove from the heat and set aside. In a glass pie dish or circular oven proof pan, layer the carrots, onions, potatoes, and beets alternatively from the outside of the pan toward the center. Brush with the rosemary butter evenly and season with a pinch of salt and pepper. Place in the oven for 45-55 minutes until cooked through and slightly crisped.