Slice each chicken breast lengthwise into two equal pieces, giving you 4 portions.
Place the chicken in a large bowl and pour the buttermilk over it. Let it marinate for about 20 minutes.
In a medium-sized bowl, combine the flour, paprika, all-purpose seasoning, salt, and pepper. Mix well and set aside.
Preheat your oven to 400ºF (200ºC).
Line a 9x13-inch baking sheet with parchment paper. Melt the butter and pour it over the parchment paper, ensuring the bottom of the pan is well-coated.
After marinating, pat each chicken breast with a paper towel to remove excess buttermilk. Then, coat each piece in the flour mixture, making sure both sides are fully covered.
Arrange the coated chicken breasts in a single layer on the prepared baking sheet. Leave a small gap between each piece to help them crisp up as they bake.
Bake for 35-40 minutes, flipping the chicken halfway through (after about 20 minutes), until the breading is golden brown and the chicken is cooked through.
Remove the chicken from the oven and transfer to a serving dish. Garnish with fresh parsley if desired, and enjoy!