Heat a non-stick skillet over medium heat and cook the turkey bacon slices until crispy, about 3-4 minutes per side. Remove from skillet and set aside on a paper towel-lined plate.
In a small bowl, whisk the eggs with a pinch of salt and black pepper.
Melt the butter in the same skillet over medium-low heat. Pour in the eggs and gently scramble them until just set but still soft, about 2-3 minutes. Remove from heat.
Toast the sourdough bread slices until golden brown.
Place one slice of toasted sourdough bread on a plate. Layer with fresh spinach leaves, scrambled eggs, turkey bacon, and cheddar cheese slice.
Top with the second slice of toasted sourdough bread to complete the sandwich.
Serve immediately while warm.