Preheat and prep: Heat your oven to 350°F (175°C).
Line a 12-cup muffin pan with paper liners or lightly coat with nonstick spray.
Mix the cinnamon topping: In a small bowl, combine 1 tablespoon granulated sugar, 2 tablespoons zero-calorie sweetener, and 1 teaspoon ground cinnamon. Set aside.
Whisk dry ingredients: In a medium bowl, whisk 1 cup white whole wheat flour (or all-purpose), 1 teaspoon baking powder, 1/4 teaspoon baking soda, 1/4 teaspoon salt, and 1 teaspoon cinnamon.
Combine wet ingredients: In a large bowl, whisk 1/3 cup unsweetened applesauce, 1/2 cup nonfat Greek yogurt, 1/3 cup zero-calorie sweetener, 2 tablespoons granulated sugar, 1 large egg white, 1 teaspoon vanilla extract, and 1/3 cup unsweetened almond milk until smooth.
Bring it together: Add the dry ingredients to the wet and stir gently until just combined. Do not overmix.
The batter should be thick but scoopable.
Portion the batter: Divide the batter evenly among the 12 muffin cups. Each cup should be about two-thirds full.
Top with cinnamon “sugar”: Sprinkle about 1/2 teaspoon of the cinnamon mixture over each muffin. Lightly swirl the top with a toothpick for a snickerdoodle look.
Bake: Bake for 12–15 minutes, or until a toothpick inserted in the center comes out clean and the tops spring back.
Avoid overbaking to keep them moist.
Optional buttery finish: For a classic snickerdoodle vibe, brush the hot muffin tops with 1 teaspoon melted light butter total (a tiny touch per muffin), then sprinkle with any remaining cinnamon mixture. This keeps them near 100 calories if used sparingly.
Cool and enjoy: Let muffins cool in the pan for 5 minutes, then transfer to a rack to finish cooling. They’ll continue to set as they cool.