In a saucepan, combine brown sugar and pineapple juice over medium heat. Simmer until thickened, about 15 minutes, then stir in softened butter and bourbon until completely mixed.

Pour the luscious caramel mixture into a greased cake pan. Gently arrange pineapple slices and maraschino cherries on top in a decorative pattern.

In a separate bowl, whisk together the all-purpose flour, baking powder, cardamom (if using), and salt.

Using a mixer, cream the softened unsalted butter and both sugars together until light and fluffy. Gradually add in the sourdough discard, eggs, pineapple juice, and vanilla extract until well combined.

Carefully fold the dry ingredients into the wet mixture until just combined.

Pour the batter over the beautifully arranged topping and bake in a preheated oven at 325°F (160°C) for 50-60 minutes.

Allow the cake to cool in the pan for about 10 minutes, then invert onto a serving platter.