01 - Preheat oven to 350°F. Grease and line an 8-inch square baking pan with parchment paper.
02 - Whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt in a large bowl until well combined.
03 - Add buttermilk, vegetable oil, egg, and vanilla extract to the dry mixture. Mix until smooth, then gradually pour in hot water while stirring.
04 - Pour batter into prepared pan. Bake for 25 to 30 minutes or until a toothpick inserted in center comes out clean. Cool completely.
05 - Whip heavy cream with powdered sugar and vanilla extract until medium-stiff peaks form. Add softened cream cheese if using and whip until smooth. Refrigerate.
06 - Break cooled cake into small pieces and crumble into fine crumbs using hands or a fork.
07 - Add a layer of cake crumbs to clean flower pots or dessert cups, followed by a layer of cream filling. Repeat with another cake layer.
08 - Generously sprinkle chocolate cookie crumbs over the top layer to resemble garden soil.
09 - Arrange edible flowers, mint leaves, and herb sprigs on top to create a whimsical potted garden appearance.
10 - Refrigerate assembled desserts for at least 30 minutes before serving to allow flavors to meld and texture to set.