Step 1

Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch rimmed baking sheet or baking pan and line with parchment paper.

Step 2

Combine butter and sugar in a large bowl. Beat with an electric mixer until light and fluffy. Add eggs one at a time, beating well after each addition.

Step 3

Mix flour and baking powder together in a bowl. Sift gradually into butter mixture, mixing well.

Step 4

Transfer 6 to 8 heaping tablespoons of the cake batter, about 1 cup, to a separate bowl. Mix in milk gradually until batter is creamy and the consistency of pancake batter.

Step 5

Spread thick cake batter into the prepared baking pan and level out with the back of a spoon. Mix applesauce and cinnamon together and spread on top in an even layer. Top with the thin cake batter.

Step 6

Bake in the preheated oven until the top of the cake is a deep golden brown, about 50 minutes. Remove from oven and allow to cool. Dust with confectioners' sugar before cutting into squares.