Heat a large skillet over medium heat. Add olive oil and butter to pan; swirl to coat.
Add onions; cook 1-2 minutes and add garlic. Stir in rice, and cook for 1-2 minutes, stirring constantly.
Increase heat to medium-high and add wine. Follow with ½ cup of stock at a time, stirring constantly until each portion of stock is absorbed before adding the next. With the last portion of stock stir in the asparagus, dill, and lemon zest.
When liquid is absorbed, remove from heat, stir in cream and Parmesan. Squeeze a lemon over the top and season with salt.
Garnish with additional dill and Parmesan, if desired, and serve.