In a small bowl, mix together all the spice blend ingredients: kosher salt, garlic powder, smoked paprika, thyme, black pepper, and cayenne.
In a medium bowl, combine 1 cup (240 ml) of buttermilk, the hot sauce, and half of the spice blend. Add the chicken pieces and stir to coat. Cover and refrigerate for at least 30 minutes or up to 1 hour.
While the chicken marinates, prepare the creamy garlic ranch. In a bowl, whisk together the mayonnaise, ¼ cup (60 ml) of buttermilk, apple cider vinegar, minced garlic, dill, scallions, salt, pepper, and Worcestershire sauce. Cover and chill until ready to serve.
Heat the oven to 250°F (120°C). Place a wire rack on a baking sheet. In a shallow dish, combine the flour with the remaining half of the spice blend. Wrap the tortillas in foil and place them in the oven to warm.
In a large, heavy-bottomed pot or Dutch oven, heat about 2 inches of oil over medium-high heat until it reaches 350°F (175°C).
Working in two batches, remove chicken from the marinade, letting excess drip off. Dredge the chicken pieces in the seasoned flour, shaking off any excess. Carefully add the chicken to the hot oil.
Fry for 6 to 8 minutes, turning occasionally, until the chicken is golden brown and cooked through. The internal temperature should reach 165°F (74°C).
Use a slotted spoon to transfer the cooked chicken to the wire rack and place it in the warm oven. Repeat with the remaining chicken.
To serve, fill the warm tortillas with the fried chicken and add your favorite toppings and a drizzle of the garlic ranch.