3/4cupunsalted butter (12 Tablespoons, or 1 1/2 sticks), softened
1 1/2cupsfull-fat sour cream
2 1/4 cups all-purpose flour
1teaspoon kosher salt
1/2cupsweetened coconut flakes, additional for garnish
3/4cupheavy whipping cream
Preheat the oven to 350 degrees Fahrenheit. Heavily coat the bottom and sides of the tube pan with cooking spray and set aside.
Cinnamon Sugar Filling and Topping
In a large bowl, whisk together all of the cinnamon sugar filling/topping ingredients except for the butter, until all of the ingredients are incorporated well. Set aside 2/3 of the mixture in one bowl (this will be the cinnamon sugar filling layer), and 1/3 in another (for the topping). Combine the 1/3 reserved amount of the cinnamon sugar mixture with the butter. You can do this with a pastry cutter, your hands, or even a food processor, until the mixture is crumbly and the butter pieces are pebble-sized. Set filling and topping aside.
Coconut Coffee Cake
In a stand mixer using the paddle attachment, cream the butter and sugar together until smooth. Add the eggs, sour cream, and vanilla and combine until ingredients are fully incorporated. Add the flour, baking powder, soda, and salt and mix until just combined. Add the coconut and mix until just combined- only a few seconds. Remove bowl from stand mixer and use a spatula to scrape the sides and bottom of the bowl, making sure all ingredients are incorporated.
Spoon 1/2 of the cake batter into the greased tube pan and spread with a spatula until even. Sprinkle the reserved 2/3 of the cinnamon sugar filling on top of the cake batter and smooth with hands or back of a spoon. Spoon the remaining cake batter on top of the filling and carefully spread this second layer of cake batter with a spatula until even. Sprinkle the reserved butter and cinnamon sugar topping evenly on top of the second layer of cake batter.
Bake the cake for 50-60 minutes, until a toothpick inserted in the center of the cake comes out clean. Cool the cake in the tube pan on a cold surface (like a countertop), or on a cooling rack. While the cake is cooling, prepare the caramel sauce.
Over medium heat, whisk together all of the caramel sauce ingredients except for the vanilla in a medium-sized saucepan. Cook until thickened and mixture comes to a soft boil, stirring occasionally. Remove from the heat and stir in the vanilla.
After the cake has cooled, use a butter knife to loosen edges if needed and invert onto a serving plate or cake stand. You can serve the cake with the cinnamon sugar topping on the bottom or the top.
Serve cake by ladling about 1/4 cup caramel sauce into a small bowl or rimmed plate and then topping with a slice of the coffee cake. You may also sprinkle coconut flakes on top of the cake for garnish. Enjoy warm.
This cake serves 8-12 people comfortably.
The cake is best day prepared the day of, but in a pinch you can make it a day ahead and serve the next day with the warm caramel sauce.