Preheat a small nonstick pan over medium heat.
Meanwhile, assemble the sandwich!
Top one slice of bread with one slice of cheese, followed by the tomato slices, baby spinach leaves, avocado slices {mash slightly to keep from slipping out of the sandwich}, jalapeno slices, alfalfa sprouts, and mushroom slices. I find that putting the bulkier sliced ingredients right next to the cheese works best!
Top with the other slice of cheese and slice of bread.
Spread 1 tablespoon of MELT buttery spread on the top slice of bread, then place the sandwich, butter-side down, in the hot pan.
While one side cooks, spread the other slice of bread with the remaining 1 tablespoon of MELT spread.
Once the cheese starts to melt and the bread is toasted, carefully flip the sandwich and finish cooking. Serve immediately!