01 -
Heat a large skillet or griddle over medium heat. You want it nice and warm but not smoking hot.
02 -
Scoop out your avocado and mash it up with a fork until it's creamy but still has some texture. Season with a pinch of salt and pepper.
03 -
Toss both cheeses together in a bowl so they're evenly mixed. This helps them melt together perfectly.
04 -
Spread softened butter on one side of each bread slice. On the unbuttered side of two slices, spread a thin layer of mayo.
05 -
Place the mayo-spread slices in your heated pan, mayo-side down. Spread the seasoned avocado evenly over each slice, then sprinkle with garlic and onion powder.
06 -
Pile on your cheese mixture generously over the avocado. If you're using basil, layer those fresh leaves on top of the cheese.
07 -
Top with the remaining bread slices, butter-side facing up. Cook for 3-4 minutes until the bottom is golden brown and crispy.
08 -
Carefully flip your sandwiches and cook another 3-4 minutes until both sides are golden and the cheese is completely melted and gooey.
09 -
Remove from heat, let cool for just a minute, then slice diagonally and serve while the cheese is still stretchy and warm.