Add 2 cups of apple cider to a saucepan and bring it to a boil. Let simmer for 20-30 minutes on medium-high heat until it’s reduced to ½ cup. Remove it from the heat and set it aside to cool.
MAKE THE MUFFIN BATTER
In a medium mixing bowl, whisk together the flour, spices, salt, and baking powder and set aside.
In a large bowl, beat the egg thoroughly with a whisk or electric mixer. Mix in the granulated and brown sugars until combined.
Stir in the buttermilk, vanilla extract, and oil. Add the applesauce and reduced cider and mix until fully incorporated.
Finally, add the dry ingredients to the wet ingredients. Use a spatula or wooden spoon to gently mix the batter just until the ingredients are combined. Be careful not to overmix.
Set batter aside to rest for 10 minutes before scooping it into the muffin tin.
MAKE THE STREUSEL
In a medium bowl, combine the flour, granulated sugar, brown sugar, and cinnamon. Melt the butter completely in the microwave and set it aside for 1-2 minutes to cool slightly.
Drizzle the melted butter over the flour mixture and gently incorporate it with a fork until the streusel forms. It will have a sandy appearance with lots of chunks.
BAKE AND COOL
Preheat oven to 350°F and lightly grease a standard 12-cup muffin tin. Scoop about ¼ cup of muffin batter into each cup, filling them about ¾ of the way full. Sprinkle 1-2 tablespoons of streusel on top of each muffin.
Bake for 15-18 minutes until they test done with a toothpick. Let muffins cool in the pan for about 5 minutes before transferring to a wire cooling rack to cool completely.
Notes
Reduce 2 cups of apple cider to ½ cup and let it cool before adding it to the batter
You can use plain or spiced apple cider
Be sure to use room temperature ingredients
Take care not to overmix the batter to avoid a tough, chewy texture
Store at room temperature in a plastic bag or airtight container for 2-3 days