Preheat the oven to 350°F. Use a serrated knife to slice the baguette in half, lengthwise. Then cut each half into serving portions, keeping the bottom of the loaf intact. Place on a baking sheet, cut side up.
In a small bowl, stir together the softened butter, garlic, and Greek seasoning until well combined. Brush the mixture over the cut sides of the bread, getting into the crevices.
Pile on the olives and sprinkle with feta. Don’t worry about making it perfect—just make sure the bread is well-covered.
Bake in the preheated oven for 20 minutes, until the edges are golden and the feta is slightly melted. Switch the oven to broil for 1–2 minutes to brown the top just a little more.
Sprinkle with chopped parsley and serve warm.