Preheat the oven to 400 ℉ and line a baking sheet with parchment paper. Line a plate with several layers of paper towels.
Cut the bacon in thin 1/3-inch strips, and cut the strips crosswise to make 1/3 inch squares. Cook the bacon in a skillet, reserving the bacon grease. Use a slotted spoon to transfer the bacon bits to the paper towel lined plate to drain. When cool, crumble finely.
In a small bowl, combine the crumbled bacon, Italian bread crumbs and Parmesan cheese. Stir with a fork to combine and reserve.
Arrange the trimmed asparagus spears in a single layer on the baking sheet
Drizzle with bacon grease and roll the spears to coat. Sprinkle with freshly ground pepper.
Sprinkle with the crumb topping, making sure the cut ends are covered to prevent the stems from drying out.
Roast until the asparagus is tender but still crisp and bright green and topping is starting to brown, about 12 minutes. (This may take a few minutes longer for thicker asparagus spears. Test a spear by taking a bite to be sure it's cooked to your liking.)
Transfer the spears to a serving plate and sprinkle with the crumbs. Garnish with lemon slices, if desired.
Store leftovers tightly wrapped in the refrigerator for up to 2 days. Reheat on a parchment-lined baking sheet in a 325 degree oven until hot, about 9 minutes.