In a small bowl, mix together the chicken, hot sauce, mayo, carrot and onion.

Lightly butter one side of two slices of the bread.

Flip the slices over and lay them butter side down on your work surface.

Sprinkle each slice with half of the cheddar, top with the half of buffalo chicken mixture, then half of the blue cheese and finally the other slice of bread.

Heat a non-stick pan over medium heat.

Place the sandwiches butter side down in the pan and cook on the first side until the bread is golden brown and toasted, about 2-4 minutes per side.

Flip the sandwiches using a spatula and continue to cook on the other side until the bread is golden brown.

You can use the spatula to compress the sandwich as it cooks on the second side.

Remove the sandwiches from the pan and let them rest for a minute or two, then slice in half (if desired) and serve.

Serve immediately.