In a small bowl combine 1/2 cup mayonnaise, 1 tablespoon minced chipotle peppers in adobo, 1 tablespoon lime juice, 1/2 teaspoon smoked paprika and 1/4 teaspoon salt. Stir until smooth and taste; adjust heat or acidity (add more chipotle or lime) as desired. Cover and refrigerate while preparing the rest.

Santa Fe Filling

Prepare filling

If using leftover or rotisserie chicken, shred or finely dice to measure 2 cups. In a bowl combine the chicken, 1 cup sliced roasted red bell pepper, 3 tablespoons chopped pickled jalapeños, 1/4 cup thinly sliced red onion and 2 tablespoons chopped fresh cilantro. Toss gently to combine. Season with a pinch of salt and 1/8 teaspoon black pepper if desired. Set aside.

Sandwiches

Assemble sandwiches

Lay out 8 slices of sourdough. Spread a generous tablespoon of the chipotle mayo on one side of each slice. On 4 slices (mayo side up) layer: 1/4 cup sharp cheddar, 2 tablespoons pepper jack, 1 tablespoon monterey jack (or distribute the combined cheeses evenly so each sandwich has about 3/4 cup total cheese), then top with a quarter of the Santa Fe filling (about 1/2 cup). Add a little extra cheddar on top of the filling to help bind. Top with the remaining bread slices, mayo side down.

Butter and grill

Heat a large nonstick skillet or griddle over medium-low to medium heat (so cheese melts before bread overbrowns). Melt 1 tablespoon unsalted butter in the pan. Place one assembled sandwich in the skillet and press gently with a spatula. Cook 3-4 minutes until the bottom is golden brown. Spread 1 tablespoon butter on the top slice while the sandwich cooks. Carefully flip and cook another 3-4 minutes, pressing occasionally, until the bread is golden and the cheese is fully melted. Adjust heat to avoid burning; reduce to medium-low if the bread browns too fast. Repeat with remaining sandwiches, adding butter as needed (about 1 tablespoon per sandwich).

Rest and serve

Transfer grilled sandwiches to a cutting board and let rest 1 minute to settle. Slice each sandwich in half on the diagonal. Serve hot with optional avocado slices, extra cilantro and lime wedges for squeezing.