Preheat oven to 400 degrees F
In 3.5 quart wide Dutch oven or any wide, heavy pan with lid, melt the butter over medium heat
Sauté onion until translucent and tender
Add rice, stirring occasionally, until rice is slightly toasted, about 2-4 minutes
Add garlic and salt (to taste), stirring until garlic is just fragrant, about a minute
Add the wine, and let cook for one minute
Stir in 3 cups of broth, turn up the heat to medium high, and bring to a simmer
Cover and place pot in oven.
Stir once halfway through cooking, after about 15 minutes
Cover pot again and continue to cook until the rice is tender and broth is absorbed, about 25-30 minutes
About 10 minutes before rice is done, coat asparagus pieces in the olive oil and spread on an aluminum-foil lined baking sheet
Sprinkle asparagus with salt
Place asparagus in oven (along with the rice) and roast until tender (about 7-10 mins)
Remove risotto from oven
Stir in remaining 1 1/2 cups warm broth, cheese, asparagus, butter pieces plus salt and freshly ground pepper to taste
Serve immediately with extra grated Dubliner Cheese, if desired.