Cut each chicken breast in half lengthwise to create two thinner fillets. In a bowl, mix together the paprika, chilli, garlic, onion, cumin, salt and pepper. Put on disposable gloves and rub the spice mixture all over the chicken, making sure it is evenly coated.
Heat the grill to medium heat and place the corn cobs on the grill. Cook for approximately 10–15 minutes, turning them 2–3 times, until cooked through and lightly charred. Set aside to cool.
Brush the chicken with a little olive oil to prevent it from sticking to the grill. Grill the chicken for 5–6 minutes on each side, until thoroughly cooked but still juicy. Cut into one of the thickest pieces to make sure the chicken is cooked through. Transfer the chicken to a baking dish and cover with aluminium foil. Let it rest for 10 minutes.
Using a knife, remove the corn kernels from the cobs and place them in a bowl. Drizzle with one tablespoon of olive oil and the lemon juice, then add the oregano, salt and pepper.
Cut the chicken fillets into small strips, similar to fajitas. Lay the 8 tortillas out on the kitchen counter or a large work surface. Place some of the chicken strips over half of each tortilla, add 1–2 tablespoons of corn and sprinkle generously with grated Cheddar cheese. Repeat until all the chicken has been used.
Fold the tortillas in half to cover the filling. Cook them over medium heat for a few minutes on each side, until golden and crisp and the cheese has melted.
Serve the quesadillas warm with guacamole and sour cream.