In a small bowl, mix the brown sugar and cinnamon. Set aside.
In a medium bowl, cream together the butter and sugar. Beat in the eggs one at a time and continue to mix. Add vanilla.
In another bowl, whisk together the flour and baking powder. Add the dry mixture to the wet, and stir until blended.
Add the milk and beat until smooth.
Sprinkle half of the brown sugar mixture into the bottom of the Bundt pan. Shake it a bit to get some of the sugar up the center post and on the sides of the pan as well.
Add 1/2 of the apples on top of the brown sugar mixture. DO NOT STIR.
Cover the apples with 1/2 of the cake batter, being sure to distribute it evenly around the pan and smooth it out. Repeat the layers. Cover the pan with foil.
Place the trivet in the bottom of the Crockpot Express and pour in 1 cup of water. Using a sling, lower the pan onto the trivet. Close and lock the lid, and switch the steam release valve to the closed position.
Press "Dessert" and set the time for 35 minutes (low pressure.) When the cooking time is up, do a quick pressure release and carefully remove the pan from the CPE with the sling. Let cool on a baking rack for at least 10 minutes.
After cooling, flip the pan over onto a plate to remove the cake. Prepare the glaze and drizzle all over the top of the cake. Serve with vanilla ice cream for an extra dose of deliciousness!