Preheat oven to 375 degrees. Line a regular size muffin tin with liners and set aside.
In a medium size bowl add the butter and light brown sugar. Mix until combined. Stir in the eggs and vanilla extract. Add in the flour, salt, baking powder, and cinnamon. Mix until well combined. Stir in the milk. Then fold in the apple chunks.
Spoon the muffin batter into the muffin liners until they are about 3/4 full. Will make 12 muffins.
In a small bowl combine the ingredients for the topping, stir together the light brown sugar, cinnamon and flour. Pour in the melted butter and stir until crumbles form.
Sprinkle a spoonful of the crumbs onto the tops of the muffins.
Bake at 375 for about 30-35 minutes, until tops are golden and a toothpick inserted into the center comes out clean.
Allow to cool in the tin for about 5 minutes, then remove to continue cooling. Serve and enjoy! Muffins will store in a sealed container for about 3 days.