Preheat the oven to 220°C (425°F). If using empty escargot shells, set them in an escargot baking dish or a shallow ovenproof dish with cavities. If using small ramekins, place one snail per cavity. Pat the escargot dry with paper towels and set aside.

Make garlic-parsley butter

In a small saucepan over low heat, melt the unsalted butter until just liquid. Add the minced garlic and minced shallot and cook gently for 1–2 minutes until fragrant but not browned. Remove from heat and stir in the chopped parsley, white wine, champagne vinegar or lemon juice, Dijon mustard, salt and pepper. Taste and adjust seasoning. Let the mixture cool slightly so it thickens but remains pourable.

Assemble

Place one snail into each shell or cavity. Spoon about 1 tablespoon of the garlic-parsley butter over each snail so the meat is well coated and the cavity is nearly full. If you like a crunchy top, sprinkle a pinch of fine breadcrumbs over each filled cavity and, if using, a small sprinkle (about 1/8 teaspoon) of grated Parmesan on each.

Bake

Set the escargot baking dish on a baking sheet to catch any butter runoff. Bake in the preheated oven for 8–10 minutes, until the butter is bubbling and the tops are lightly golden. If you prefer extra browning, switch to broil for 30–60 seconds—watch carefully to avoid burning.

Rest

Remove from oven and let rest for 1–2 minutes. The butter will be very hot; allow a short cool-down before serving.

To Serve

Arrange the escargot on a warmed serving plate. Serve immediately with toasted baguette slices to dip into the garlic butter and lemon wedges on the side. Optionally garnish with a few extra chopped parsley leaves and the thinly sliced shallot for brightness.