Prep the pan: Heat the oven to 350°F (175°C).
Lightly grease a mini muffin tin or line with paper cups.
Mix dry ingredients: In a medium bowl, whisk 1/2 cup rolled oats, 3/4 cup whole wheat flour, 1 teaspoon baking powder, 1/4 teaspoon baking soda, 1/4 teaspoon fine salt, and 1 teaspoon cinnamon.
Whisk wet ingredients: In a large bowl, whisk 1/2 cup plain Greek yogurt, 1/4 cup honey, 1/4 cup unsweetened applesauce, 1 large egg, 1 teaspoon vanilla, 2 tablespoons neutral oil, and 2–3 tablespoons milk until smooth.
Combine: Add the dry mix to the wet. Stir gently with a spatula just until no dry streaks remain. If the batter seems thick like cookie dough, add another tablespoon of milk.
It should be thick but spoonable.
Optional add-ins: Fold in up to 1/4 cup total of extras (mini chocolate chips, blueberries, or finely chopped nuts). Keep it light to stay under 100 calories per mini muffin.
Portion: Spoon the batter into the mini muffin cups, filling each about 3/4 full. You should get about 18–22 mini muffins, depending on your pan.
Bake: Bake for 10–13 minutes, or until the tops spring back lightly and a toothpick comes out clean or with a few moist crumbs.
Cool: Let the muffins rest in the pan for 5 minutes, then transfer to a rack to cool completely.
This helps them stay moist without getting soggy.