Spread brie on one slice of ciabatta, scatter the sun-dried tomatoes over it, and top with a slice of sharp cheddar.
Heat a pan over medium heat and add a good drizzle of olive oil. Once the oil is shimmering, add the sandwich and cook until the bottom is deep golden brown and crisp.
If the pan looks dry, add a small drizzle of oil, then flip the sandwich once. Cook until the cheese is fully melted and the bread is equally golden. If the bread browns faster than the cheese melts, turn the heat down a little.
Cut the sandwich in half before serving so the steam escapes and the middle doesn't go soggy.