In a small bowl or jar, stir together the ranch ingredients until smooth. Taste and add salt as needed, then refrigerate until ready to use.
Pat the chicken dry, then season both sides with salt and black pepper.
Heat avocado oil in a large skillet over medium heat. Add the chicken and cook for about 5–7 minutes per side, or until golden brown and the internal temperature reaches 165°F. If the chicken breasts are thick, reduce the heat slightly and cover the skillet for a few minutes to help them cook through without burning.
Transfer the chicken to a cutting board and let it rest for 5 minutes. Chop into small bite-sized pieces. Toss the chopped chicken with 1–2 tablespoons of the ranch, just enough to lightly coat it.
Wipe out the skillet if needed and reduce the heat to medium-low. Brush each side of bread with oil.
Build each melt with one slice of bread, oil-side down, followed by provolone, chopped chicken, bacon, a light drizzle of ranch, chopped kosher pickles, pepper jack, and the second slice of bread, oil-side up.
Add the sandwiches to the skillet and cook for 3–4 minutes per side, or until the bread is golden brown and crisp and the cheese is melted. Work in batches if needed.
Let the melts rest for 1–2 minutes, then slice and serve with extra ranch for dipping.