1. Whisk together the buttermilk, hot sauce and 1 1/2 teaspoons salt in a large mixing bowl. Add the chicken and turn to coat evenly. Cover the bowl with plastic wrap and refrigerate for at least 2 hours and up to overnight.
2. Meanwhile, make the maple butter. Combine the syrup and salted butter in a small mixing bowl. Stir until smooth and creamy. Cover with plastic wrap and keep at room temperature until ready to use.
3. Preheat the oven to 120°C. Preheat a 6 1/2-inch round waffle iron to medium-high heat and spray with nonstick spray. Make the waffle batter according to the package directions, and then cook the waffles to desired doneness.
4. Transfer to the oven to keep warm while frying the chicken.
5. Fill a large Dutch oven halfway with rapeseed oil and heat to 190°C.
6. While the oil is heating up, combine the flour, 1 pinch salt and 1 pinch pepper in a large resealable plastic bag. Seal the bag and shake to combine.
7. Remove the chicken from the buttermilk and transfer to the bag of seasoned flour, letting any excess marinade stay behind in the bowl. Seal the bag and shake until all of the chicken is evenly coated.
8. Transfer the chicken back into the bowl of marinade, tossing gently to coat. Return the chicken to the seasoned flour, seal the bag and shake again to evenly coat. Transfer the chicken to a rack set over a baking sheet in a single layer and let sit for 15 minutes. Fry the chicken in batches until golden brown and cooked through, 6 to 8 minutes per batch.
9. Make sure that the oil comes back to temperature after each batch. Transfer the chicken to a large paper-towel-lined plate using a slotted spoon or tongs to absorb any excess oil. Season liberally with salt.
10. To assemble, cut each waffle into quarters. Sandwich 1 piece of fried chicken between 2 waffle pieces slathered with the maple butter. Continue to assemble sandwiches with the remaining chicken, waffles and maple butter.
11. Serve immediately with your favorite hot sauce on the side.