MELT butter with olive oil in a deep skillet on medium heat. Add onion and garlic; cook 2 to 3 minutes. Do not brown.
TOSS in rice and stir to coat the rice. Add warm broth, milk and asparagus.
BRING to a boil over medium heat; simmer for 5 minutes over low heat. Mix in 1/4 cup of the Parmesan cheese, salt and pepper. Sprinkle with remaining Parmesan cheese just before serving.