Preheat Oven: Preheat the oven to 350°F. Grease an 8×8 or 9-inch round cake pan (ensure the pan has a capacity of 8 cups).

Prepare the Banana Layer: Spread the brown sugar evenly on the bottom of the pan, then scatter the butter pieces over it. Bake for 5-7 minutes until the butter has melted. Stir to combine the sugar and butter, then arrange the banana slices in a single layer on top.

Make the Cake Batter: In a bowl, mix together the dry ingredients: all-purpose flour, whole wheat flour, baking powder, baking soda, salt, and cinnamon.

Cream Butter and Sugar: In a large bowl, cream together the softened butter and sugar. Add the eggs and vanilla, mixing until smooth. Stir in the Greek yogurt and mashed bananas.

Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the wet ingredients, mixing just until combined.

Assemble the Cake: Pour the batter over the caramelized bananas, smoothing the top with a spatula.

Bake: Bake for 30 minutes at 350°F, then reduce the temperature to 325°F and bake for another 25-35 minutes, or until a toothpick inserted into the center comes out clean.

Cool and Invert: Let the cake cool slightly before inverting onto a plate. Use a knife to loosen the edges, then place a plate upside down over the pan and carefully flip the cake.

Make the Caramel Glaze: In a saucepan, combine the butter, brown sugar, heavy cream, and salt. Bring to a boil over medium heat, stirring constantly. Simmer for 2-3 minutes and remove from heat.

Serve: Let the glaze cool for 1-2 minutes, then pour two-thirds of it over the banana layer. Reserve the rest for serving. Reheat the remaining glaze and drizzle it over each slice. Optionally, sprinkle with toasted chopped pecans or serve with vanilla ice cream or whipped cream.