Preheat the oven to 390°F (200°C).
Melt the butter. You can do so in a small pot over low heat or in a microwaveable bowl in the microwave, in 15-second increments until melted (carefully so it doesn’t make a mess in the microwave).
Add the minced garlic, grated parmesan, lemon zest, lemon juice, salt, pepper, and finely chopped fresh basil.
Slice the baguette only 3/4th of the way into slices that are about 3/4 inch thick (about 2 cm).
Brush it with the butter mixture both on top and in the cuts (in between all the slices). If using an already-baked bakery baguette, wrap it in foil. If using part-baked (bake-at-home) baguettes, you don’t need to wrap them in foil.
Bake the baguettes at 390°F (200°C) for about 15 minutes.
Once baked, unwrap from the foil and serve hot.