Preheat oven to 350 degrees F (180 degrees C).
Whisk together All-Purpose Flour (2 1/2 cup), Baking Soda (1/4 teaspoon), Baking Powder (1 teaspoon), Fine Sea Salt (1 1/4 teaspoon), Ground Cinnamon (2 teaspoon), then set aside.
Add the Granulated Sugar (1 cup), Brown Sugar (2 cup), and Unsalted Butter (1 1/2 cup) the bowl of the stand mixer. Using the paddle attachment, cream the butter for 4 minutes.
In another bowl, whip the Heavy Cream (1/2 cup) until it begins to thicken.
After 4 minutes, scrape the butter and sugar mixture down. Add Vanilla Extract (2 teaspoon) and let the mixture mix for another 4 minutes.
Drizzle a little bit of the Egg (5) into the mixture for about 10 minutes. Scrape the mixture down one final time and quickly mix it.
Add the 1/2 of the flour mixture and then mix. When the flour mixture dissolves, scrape the bowl again before adding 1/2 of the Buttermilk (3/4 cup). Repeat with the remaining flour and buttermilk.
Pour the whipped cream mixture and fold it into the batter.
Pour the finished mixture into a 10-inch bundt pan until it fills half of the pan and smooth the top of the batter. You can use a loaf pan or a cupcake pan for the remaining mixture.
Bake for 30 minutes.
Let cool for a few minutes before flipping over onto a plate. Top with Vanilla Frosting (to taste) or frosting of choice, then slice and serve!