Preheat the oven to 350°F. Split the bread lengthwise and place, cut side up, on a foil-lined baking sheet.
In a small saucepan, melt the butter. Add the ranch seasoning mix and let simmer together for about 1–2 minutes until the flavors are blended.
Brush the ranch butter evenly over the cut sides of the bread. Spread the garlic Ranch dressing over the butter and sprinkle cheese evenly over the top.
Bake for about 15 minutes, until the cheese is mostly melted. Move the tray to the very top rack and turn on the broiler. Broil for about 2–3 minutes, until the cheese is brown and bubbly, taking care not to burn the cheese.
Remove the bread from the oven and let sit until cool enough to handle, no more than 5 minutes. Garnish with chopped parsley. Slice and serve immediately.