Preheat oven to 450F. Combine 1 cup milk and 3 eggs in a blender. Blend 1 min. Add 1 cup all-purpose fl our, 1 tbsp melted butter and 3/4 tsp salt. Blend 1 min. Let batter stand. Spoon 1/2 tsp vegetable oil into each of 10 cups of a 12-cup muffin pan. Heat pan with oil in it in oven for 15 min. Pour batter into cups, to about 3/4 full. Sprinkle with 1/4 cup finely chopped chives. Bake for 20 min. Without opening oven door, reduce heat to 350F. Bake until popovers are puffy, about 15 more min.