Season to taste with salt and pepper. Melt butter in a large skillet over medium heat. Stir until almonds begin to color, about 2-3 minutes. Sprinkle remaining 1 tbsp sugar over. Stir until sugar melts and begins to turn golden, about 2 minutes longer.
Transfer almonds to bowl and cool.
Combine spinach and apples in a large bowl. Toss with enough dressing to coat. Mix in almonds. Serve immediately, passing remaining dressing. All rights reserved.