Heat the oven to 400°F (200°C) and line a baking sheet with foil or parchment. Slice the baguette diagonally into 1-inch (2.5 cm) pieces, cutting almost but not completely through the loaf.

In a bowl, combine the softened butter, minced or grated garlic, finely chopped rosemary, salt, pepper, and optional parsley and Parmesan until evenly mixed.

Spread the garlic-rosemary butter generously between each slice and across the cut surfaces. Place the prepared loaf on the lined baking sheet.

For a softer center, wrap the loaf loosely in foil and bake for 8–10 minutes. Open the foil and continue baking uncovered for another 3–5 minutes, until the edges are crisp and golden.

For maximum crispness, bake the loaf uncovered for the full 10–15 minutes. If deeper browning is desired, broil for 30–60 seconds while watching closely, then serve hot.