Mix together the sauce ingredients and refrigerate until needed.

Preheat your air fryer to 200°C (or your oven).

In a small pan, cook the onion and bacon bits (without oil, as the bacon will release fat) until they reach your desired level of crispiness. Remove from the heat and set aside.

Place the cut chips into a microwave-safe bowl and microwave for 7 minutes.

Once out of the microwave, season with salt, spray with a few spritzes of oil, and spread them in a roughly even layer in the air fryer. Cook for 15-20 minutes, tossing every 5 minutes and adding more oil spray if needed.

Transfer the cooked fries to an ovenproof dish. Top with the bacon and onion mixture, then sprinkle with cheddar cheese.

Place the fries under the grill for 5-7 minutes (or until the cheese is melted and bubbling).

Sprinkle with sliced spring onion and chives, dollop with the spicy mayo, and serve immediately.