Apple-Oatmeal Muffins

Preheat the oven to 350 degrees F (175 degrees C). Line 18 muffin tin cups with cupcake papers.

Mix brown sugar, all-purpose flour, and cinnamon together in a small bowl for crumb topping. Add butter and press with the back of a spoon or your fingers to incorporate it into the sugar mixture. Mix until crumbly and set aside.

Toss apples with lemon juice in a large bowl. Mix in sugar, honey, buttermilk, oil, eggs, and vanilla until combined. Stir in oats.

Combine whole wheat flour, baking powder, cinnamon, baking soda, nutmeg, and salt in a smaller bowl. Gently fold flour mixture into the wet ingredients with a large spoon, until flour is just mixed in. Spoon batter into the prepared cupcake papers and sprinkle about 1 teaspoon crumb topping on top of each one.

Bake in the preheated oven until tops spring back when lightly pressed, 20 to 25 minutes. Cool on a wire rack.