Preheat the oven to 350 degrees Fahrenheit. Grease a 9x13 inch baking pan.
Melt the butter and pour it into the pan, spreading it out evenly across the surface.
Sprinkle the brown sugar over the melted butter and pat it down.
Drizzle the bourbon onto the brown sugar and tilt the pan to spread it around. Pat down and redistribute the brown sugar evenly if it moved.
Lay the orange slices evenly across the surface and set aside.
Sift together the flour, baking powder, baking soda, and salt into a medium bowl.
Cream the butter and sugar together until smooth.
Add the eggs one at a time until just combined.
Mix the vanilla extract in.
Alternate adding the buttermilk and the flour mixture until everything is combined.
Pour and scoop the batter over the orange slices and spread evenly.
Bake for 50 to 55 minutes or until the cake is done and a toothpick inserted in the center comes out clean.
Run a knife around the sides of the pan. Place a heatproof serving plate upside down onto the pan and turn the plate and pan over.
Leave alone for 5 minutes and then remove the pan. Make the Old Fashioned Hot Butter Sauce while waiting.
Use a fork to poke holes in the cake. Don't worry about ruining how the cake looks, you don't notice the holes. Pour the Old Fashioned Hot Butter Sauce over the cake and serve.
Combine the butter, sugar, bourbon, freshly squeezed orange juice, and orange zest in a small saucepan. Cook on medium heat until the butter is melted and the sugar is completely dissolved. Add a couple of dashes of the orange bitters and Angostura Bitters. Pour over the cake.
Oh and I can't forget:
OLD FASHIONED RECIPE:
Place a large ice cube in a rocks glass. Pour the bourbon and gum syrup in and stir for about 10 seconds.
Add a couple of dashes of orange and Angostura bitters.
Use a vegetable peeler to peel off a strip of orange. Twist it over the rocks glass and drop it in. Stir for 15 seconds and serve.