Preheat oven to 350 degrees Fahrenheit.
While the oven is preheating, simmer the apple cider over medium heat for about 25 minutes. You want the apple cider to be concentrated, so that you end up with about 1½ cups.
3 cups apple cider
Once the apple cider has been concentrated, let it cool.
Shred the apples with a grater (skin and all).
1 cup shredded apples
In a large bowl, mix together all of the dry ingredients.
2 cups white flour, 1 tsp baking soda, ¾ tsp baking powder, 1 tsp cinnamon, ½ tsp nutmeg, ¼ tsp cardamom, ¼ tsp salt, ½ cup brown sugar
Add the wet ingredients and mix to combine.
¼ cup skim milk, 1 tsp vanilla extract, 1 egg, 4 Tbsp butter
Divide the batter evenly into the muffin tin.
In a small bowl, mix together all of the streusel ingredients.
2 Tbsp butter, ¼ cup flour, ¼ cup brown sugar
Top the batter with the streusel topping.
Bake at 350 degrees Fahrenheit for 25 minutes.