Preheat the oven to 400 degrees. Line a large rimmed baking sheet with parchment paper and set aside. Thoroughly rinse the asparagus and pat dry with a clean kitchen towel. Cut off any wooden and hard end pieces. Spread the asparagus on the baking sheet. Season lightly with salt and coat lightly with olive oil. Roast the asparagus for 15 to 20 minutes until they are slightly browned and tender.
During the last 5 minutes of the asparagus' roasting time, melt the butter in a large skillet over medium heat. Add the shallots and the garlic scapes. Season with salt and pepper to taste. Cook and stir for 3 minutes, then remove the skillet from the stove.
When ready, remove the asparagus from the oven and transfer to a large serving plate. Evenly top the asparagus with the buttered onions and garlic scapes. Serve immediately.
If you can't find garlic scapes, simply replace them with 3 garlic cloves, chopped!
Serve these alongside a show-stopping main dish like short ribs. Leftovers taste great mixed into eggs.