Preheat the oven to 350 degrees F.
In a large bowl, beat the butter, brown sugar, and granulated sugar with an electric mixer, until well combined.
Add the eggs, one at a time, beating down the edges of the bowl as needed.
Add the vanilla, and beat to combine.
Add the cinnamon, nutmeg, baking powder, baking soda, and salt, and beat to combine.
In a small bowl, whisk together ¼ cup of the apple cider concentrate with the buttermilk.
Add 1 cup of flour to the large bowl and mix until just combined, followed by ½ of the concentrate/buttermilk mixture, mixing until just combined.
Repeat with the remaining flour and apple cider concentrate/buttermilk mixture.
Spray a 12-muffin muffin pan with cooking spray and fill each one up ½ way.
Bake in the preheated oven for 15-17 minutes, until the muffins are slightly golden, puffed up, and baked through.
Let them cool for 5 minutes.
Meanwhile, melt the butter, and combine the sugar and cinnamon in a shallow bowl, for dipping the muffins.
After the muffins are slightly cooled, brush each one with melted butter and then dip in the cinnamon sugar mixture. I like to get the entire muffin covered in sugar.
Serve, and enjoy!