Add pistachios to the bottom of a large or small food processor. Pulse until the pistachios are finely chopped and almost ground. Be careful you don't process them too much or they wiill start to turn to butter. Add softened goat cheese, greek yogurt, lemon zest, garlic, and salt. Blend until smooth. Season to taste with salt and freshly cracked black pepper.
Add lemon juice, dijon, honey, and olive oil to the bottom of a large bowl. Whisk to combine. Season with salt and pepper. Add the butter lettuce and gently toss in the vinaigrette.
Spread the goat cheese on one side of all the bread slices. Lay down one thin layer of red peppers on three of the pieces of pread. Layer cucumbers on top, followed by the spinach, and dressed butter lettuce. Top with the other piece of goat cheese slathered bread. Press down to make all the ingredients compact. If needed, secure with tooth picks. Slice down the middle and serve.