Trim the woody ends from the asparagus (usually the bottom 1-2 inches). Mince the garlic finely and combine it in a small bowl with the salt, pepper, Italian seasoning, and red pepper flakes—this ensures the seasonings distribute evenly. I prefer mixing the dry seasonings with the garlic ahead of time so they coat the asparagus uniformly rather than settling unevenly.

Heat your grill to medium-high or preheat your oven to 425°F. While it heats, spray 4 large squares of foil (about 12x12 inches each) lightly with cooking spray. Divide the trimmed asparagus evenly among the 4 foil squares, arranging them in a single layer. Sprinkle each portion with the garlic-seasoning mixture from Step 1, then top each pack with 2 teaspoons of butter and 3-4 lemon slices. Fold the foil edges up and over to create a sealed packet, leaving some room for steam to circulate inside.

Place the foil packets directly on the grill grates (or on a baking sheet in the oven). Cook for 15 minutes total—if grilling, flip the packets halfway through to ensure even cooking and help develop those charred, caramelized flavors on both sides. I like grilling over oven baking because the direct heat creates a subtle char that complements the lemon beautifully.

Carefully open the foil packets (watch for the steam!) and stir the asparagus gently to redistribute the butter and seasonings. Top each portion generously with fresh parsley for a bright, herbaceous finish. Serve directly in the foil packets for a rustic presentation, or transfer to a serving platter if you prefer.