Brown Butter Apple Cider Donut Cake

Apple Cider Cake
2 Preheat the oven to 350 F and place a rack in the center of the oven. In a medium mixing bowl add in the brown sugar, white sugar, salt, cinnamon, nutmeg, and all spice.
3 In a medium pot add in the butter and turn the heat onto medium low. We are browning the butter. First it will melt, then be loud and popping.
4 Then it’ll quiet down and foam – at this point you want to stir it and scrape the bottom of the pan. It will foam again and this time brown bits should rise to the top. At this point your butter is brown but not before!
5 Set your mixing bowl on the scale and zero it out. Pour the brown butter into the bowl it should weigh about 180-185 grams. Immediately pour oil into the bowl so the total weight becomes 225 grams. If you "mess this up" don't stress just pour 40 grams of oil into the bowl after the brown butter.
6 Whisk to combine and then add in the vanilla and three eggs. Whisk again before pouring in the apple cider and apple sauce.
7 Lastly add in the flour, baking soda, and baking powder. Whisk until just mixed.
8 Line two 8" metal round pans with parchment in the base. Pour half the batter into each pan, it should be about 630 grams of batter.
9 Bake both pans in the preheated over for 15 minutes. Then rotate 180 degrees and bake for another 10-15 minutes until a toothpick inserted in the center comes out clean.
10 Take the baked cakes out of the oven and let them cool in the pans for 15 minutes. Flip the semi cooled cakes out of their pans onto a wire cooling rack. Set them aside while prepping the cinnamon sugar. Don't leave to cool for more than 5-10 minutes.
Cinnamon Sugar Coating
12 Pour 100 grams of apple cider into a small bowl and set aside.
13 In a shallow wide bowl or a quarter sheet pan, add in the sugar and cinnamon for the coating; toss together to combine.
14 Brush the surface of one of the cakes with a bit of apple cider and let it run down the sides.
15 Gently pick up the cake and roll the sides like a wheel in the cinnamon sugar. Then flip it so the top side is face down into the cinnamon sugar and swirl it around a couple of times.
16 Carefully flip the cake over so the base is now in the cinnamon sugar. Sprinkle the top with cinnamon sugar as needed if any spots are missed. Then transfer the cake back to the wire cooling rack.
17 Repeat for the second cake round and let them cool COMPLETELY.
Brown Butter Buttercream
19 In a large pot add in the butter and turn the heat onto medium low. We are browning the butter. First it will melt, then be loud and popping.
20 Then it’ll quiet down and foam – at this point you want to stir it and scrape the bottom of the pan. It will foam again and this time brown bits should rise to the top. At this point your butter is brown but not before!
21 Pour the brown butter into the bowl of your stand mixer or a large mixing bowl and let it cool stirring every 10 minutes until it is very thick - basically we want it to be back to softened butter consistency.
22 Add in the powdered sugar and vanilla. Start on low speed, slowly increasing, beating until everything is smooth and the color has lightened.
23 Scrape down the sides and bottom of the bowl and add in the sour cream. Mix again beating this time on medium high for two minutes until light and fluffy.
24 I like to use the #789 piping tip for icing this cake but you can also just use a spoon!
25 Transfer one layer of the cake onto a large plate or cake stand (wherever you plan to serve it from). Spoon or pipe half of the frosting onto the bottom layer. Place the second layer of cake over the frosting and then top with the second half of the frosting.
26 Serve immediately!
27 Leftovers can be stored at room temperature in an airtight container just note that the sugar coating will likely soak into the cake but it will still be delicious.