Beat the butter and sugars together for 3 minutes. Scrape down the sides of the bowl and add one egg and mix until combined then add the remaining two eggs, one at a time.
Add a ⅓ of the dry ingredients to the butter mixture, mix until just combined, add half of the apple cider mixture, and mix until just combined, then repeat
Use a pastry brush to brush the melted cider/ butter mixture all over the bundt cake, after a few brushes take some of the cinnamon sugar and press it into the cake. Repeat until all of the cake is covered.