1. Begin by marinating the chicken. Pour the buttermilk into a large bowl and season generously. Add the chicken thighs, making sure they are totally covered. Cover and chill for at least 4 hours or overnight.
2. To make the waffles, preheat the oven to 110°C. Sift 125g of the flour into a large bowl. Add the baking powder, sugar, 1/2 tsp salt and a good grinding of black pepper. Mix well, then make a well in the centre of the bowl. Add the egg, milk and melted butter and whisk to form a thick batter. Fold in the crumbled bacon, spring onions and cheddar cheese.
3. Lightly grease your waffle maker with cooking spray or brush with a little melted butter. Pour a ladleful of the batter into each well then close and cook until crisp and golden. Set the waffles aside and repeat until you have used up all the batter, keeping them warm in the oven while you get on with the chicken.
4. Remove the chicken from the fridge about 30 mins before you are ready to fry. Begin by heating the oil in a large heavy duty pan. It should reach about 170°C or until a cube of bread goes golden and crispy within a minute. Place a wire rack over an oven tray and set aside.
5. Tip the remaining flour onto a shallow dish with the smoked paprika, garlic granules, 1/2 tsp salt and plenty of black pepper. Dip each piece of buttermilk chicken in the mixture to thoroughly coat then transfer to a plate. Once the oil has reached the right temperature, fry the chicken pieces until crisp and golden, about 8-10 minutes. Place on the wire rack to drain while you assemble the sandwich.
6. To serve, layer a waffle with fried chicken, Sriracha Mayo, lettuce, tomato and avocado and sandwich with another waffle, using a toothpick to hold together. Serve with coleslaw and corn on the cob.