Preheat oven to 375F. Brush or spray a ~9x11 baking dish with olive oil.
Slice the lemon in half. Juice half the lemon to make ~1 tablespoon lemon juice. Slice the other half of the lemon into 3-4 thin slices.
Cook the bacon, then place on a paper towel to absorb the extra grease and cool down. Crumble the bacon.
In a small food processor, combine the cooked crumbled bacon, parsley, lemon juice, and Parmesan and pulse for several seconds until everything is broken up and mixed together. Transfer the bacon mixture to a medium bowl and stir in the Panko breadcrumbs.
Arrange the trimmed asparagus on the baking sheet. Season with salt and pepper, and give it a gentle shake to spread the seasonings around. Top the asparagus with crispy bacon topping and lemon slices (see photos in blog post).
Roast at 375F for 15-20 minutes, or until the asparagus is cooked to your liking and the bacon topping is crispy and browned on top.
Serve topped with fresh parsley, grated parmesan, and lemon slices for garnish.
Got leftovers? Reheat in the oven for 5-10 minutes at 350F to crisp up the topping.