Prep your pan and oven. Heat the oven to 350°F (175°C).
Line a mini muffin tin with liners or coat with nonstick spray.
Mix the dry ingredients. In a bowl, whisk flour, baking powder, baking soda, and salt. This keeps the crumb light.
Whisk the wet ingredients. In another bowl, whisk Greek yogurt, applesauce, sugar, egg white, vanilla, and almond milk until smooth. The mixture should be pourable but not runny.
Combine gently. Add dry ingredients to wet and stir with a spatula just until no streaks of flour remain. Do not overmix or the muffins get tough.
Make the cinnamon swirl. Stir brown sugar, cinnamon, and melted light butter until sandy and fragrant.
Layer the batter and swirl. Fill each muffin cup halfway with batter.
Sprinkle a pinch of cinnamon mixture over each. Top with a little more batter (about 3/4 full). Use a toothpick to give each muffin a quick swirl.
Bake. For mini muffins, bake 10–12 minutes, until the tops spring back and a toothpick comes out clean.
For small standard muffins, 13–15 minutes.
Cool briefly. Let muffins rest in the pan for 5 minutes, then transfer to a rack.
Glaze. Mix powdered sugar, vanilla, pinch of salt, and milk to a drizzle. Adjust thickness with a few drops of milk as needed. Drizzle over warm (not hot) muffins so it sets nicely.
Enjoy. Serve warm for the best cinnamon roll vibe.