Place an oven rack in the middle of the over and heat your broiler to the high setting. Place the french bread, cut-side up, on a baking sheet and set in the oven for 2 minutes, then rotate and broil 2 minutes more, just until slightly golden. Remove and let cool.
Heat a large skillet over medium-high heat and add olive oil. Toss chicken with salt and pepper, then add to the skillet and cook until browned on all sides, about 10-12 minutes. Once cooked through, add garlic and stir for 30 seconds, then add in buffalo wing sauce and butter. Stir to toss and coat.
Brush 1 1/2 tablespoons (or more if desired) of ranch dressing onto each cut side of french bread. Top with 2-3 tablespoons each of buffalo wing sauce, then cover equally with a light sprinkling of fontina. Add the chicken, spooning out all of the sauce in the skillet. Cover with remaining fontina and gorgonzola. Broil on high (on the same center rack) for 5-6 minutes, watching closely and rotating the pan once or twice during broiling. You must watch closely because all broilers differ! It may take your oven 3-4 minutes or closer to 8. Just cook until the cheese is melted and slightly golden and the bread is somewhat crunchy.
Remove and top with another drizzle of buffalo wing sauce and then cover in green onions and cilantro. Cut into pieces and serve!