1cupunsalted butter(2 sticks), at room temperature
2teaspoonspure vanilla extract
Zest of 1 orangeoptional
2largeeggsat room temperature
4largebananasvery ripe, mashed (1 1/2–1 3/4 cups)
1cupnonfat plain Greek yogurtplus 2 tablespoons, at room temperature
FOR THE CREAM CHEESE FROSTING:
4ouncesreduced-fat cream cheeseat room temperature (do not use fat free)
3tablespoonsunsalted butterat room temperature
1tablespoonvanilla bean pasteor extract
Center a rack in the oven and preheat to 350 degrees F. Generously grease a 9- to 10-inch (12-cup) bundt pan.
In a medium bowl, whisk together the all-purpose flour, white whole wheat flour, baking soda, and kosher salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment or a large mixing bowl, beat the butter until smooth and creamy, about 1 to 2 minutes. Add the granulated sugar and cream into the butter at medium speed until pale and fluffy, 2 to 3 additional minutes, stopping to scrape down the bowl as needed.
Beat in the vanilla and orange zest. Scrape down the bowl, then add the eggs one at a time, beating for about 1 minute after each egg is added. Reduce the mixer speed to low and mix in the mashed bananas.
With the mixer still on low, add half of the dry ingredients (the mixture may look curdled), mixing just until combined, then add the yogurt, followed by the rest of the flour mixture.
Transfer the batter into the prepared pan, then tap the pan on the counter a few times to remove any of the bubbles. Smooth the top.
Place the pan directly on the oven rack (do not use a baking sheet) and bake for 60 to 70 minutes, until a thin knife inserted deep into the center of the cake comes out clean (the baking time can vary based on the moisture content of your bananas, so be sure to check it early to ensure it doesn't overbake, and don't be afraid to go a few minutes longer if the knife is not yet coming out clean). Check the cake at the 30-minute mark; if it is browning too quickly, tent it loosely with foil.
Transfer the cake to a wire rack and let cool for 10 minutes, then gently unmold it onto the rack to cool completely. If you have time, wrap the cooled cake in plastic and allow it to sit overnight before serving—it's even better the next day.
To prepare the frosting, beat the cream cheese and butter on medium speed until smooth and combined, about 1 to 2 minutes. Reduce the mixer speed to low. Gradually add the powdered sugar, then the vanilla bean paste and salt. Increase the speed to high, and continue beating until completely smooth and combined.
Spread the frosting over the cooled cake, cut into slices, and enjoy.
TO MAKE AHEAD: This cake tastes even better the next day! If time allows, wrap the unfrosted cake in plastic and let it sit overnight at room temperature. Frost the next day.
TO STORE: Keep leftovers loosely wrapped in plastic in the refrigerator for 3 to 4 days.
TO FREEZE: Freeze, either frosted or unfrosted, for up to 3 months. Let thaw overnight in the refrigerator. Serve at room temperature.
TO BAKE AS MUFFINS: Cut the ingredients for the batter in half and prepare as directed. To bake, grease a standard 12-cup muffin tin and place it into an oven, preheated to 350 degrees F, for 28 to 32 minutes. Muffins are ready when a toothpick inserted in the center comes out clean.