Preheat your oven to 400 degrees. Line a large baking sheet with foil for easier clean up.
Place the potatoes & asparagus in a single layer on the baking sheet. Space the cubed butter out across the veggies. Sprinkle with the minced garlic & squeeze the juice from 1 lemon over the potatoes & asparagus.
Bake for 40 - 50 minutes or until the potatoes are tender & the asparagus is just beginning to brown. Remove from the oven & squeeze the juice from the remaining lemon over the asparagus & potatoes. Serve hot.