Heat the olive oil in a frypan over medium heat. Cook the sausage in the hot oil until lightly browned, about 5 minutes. Add the garlic, salsa, chilli powder, pepper, garlic salt and cumin; cook and stir until the garlic has mellowed, about 4 minutes. Place a tortilla onto a microwave-safe plate and top with the sausage mixture. Sprinkle with the grated cheese.
Cook the tortilla in the microwave on High until the cheese melts, 45 seconds to 1 minute, depending on the microwave. Sprinkle the corn chips on top of the melted cheese and top with the remaining tortilla. Butter both sides of the quesadilla and place in a clean frypan over medium heat. Cook until golden brown; flip and continue cooking until golden brown on the other side, about 4 minutes per side. Cut into quarters to serve.