If your chicken isn't already seasoned, toss the sliced chicken in a small bowl with a pinch of salt, pepper, and a dash of chili powder. If it's cold, warm it slightly in the microwave for 30 seconds to speed up melt time.

In a small bowl, mix the mayonnaise with the chipotle in adobo paste. Taste and adjust spice level; add a squeeze of lime juice for richness if desired.

Lay out the four slices of sourdough bread. Spread a generous layer of chipotle mayo on the inside of two slices. Place one slice of cheese on the inside of the other two slices.

On top of each cheese slice, layer half the seasoned grilled chicken, keeping it centered. Add half the sliced avocado on top of the chicken for each sandwich. Sprinkle a tiny pinch of salt over the avocado to enhance flavor.

Place the remaining slice of cheese over the avocado and chicken on each sandwich for a gooey barrier.

Close each sandwich with the mayo-spread slice. Generously butter the outside of both sides of each sandwich.

Heat a skillet or griddle over medium-low heat. Place a sandwich on the hot surface and press down lightly with a spatula. Cook for 3-4 minutes per side until golden brown and cheese is melted. Repeat for the second sandwich.

Remove from heat, let rest for 30 seconds, then slice diagonally. Serve immediately for optimal warmth and crunch.