Season the chicken breast with salt, pepper, garlic powder, and paprika.

Heat olive oil in a skillet over medium‑high heat. Add chicken and cook 4–5 minutes per side, until golden brown and cooked through (internal temperature 165 °F/74 °C). Remove, let rest 2 minutes, then slice thinly.

Butter one side of each slice of bread.

Warm a clean skillet over medium heat. Place one bread slice, buttered side down, in the skillet. Add one slice of cheese, then layer on sliced chicken and optional veggies, then remaining slice of cheese. Top with the second bread slice, buttered side up.

Cook 3–4 minutes, until bottom is golden and cheese begins to melt. Carefully flip sandwich and cook another 3–4 minutes until both sides are golden and cheese is fully melted. If the exterior browns too quickly before cheese melts, reduce heat and cover pan for a minute.

Remove from heat, let rest 1 minute, then cut in half and serve hot.