• Preheat the oven to 350.
• Spray a 9-inch cake pan with baking spray.

To make the cake

• Combine the cornmeal, flour, baking powder, baking soda, and salt, and whisk together. Cream the butter with a stand mixer and the paddle attachment. You want to get the butter good and fluffy so do this for a few good minutes. Then add the sugar and continue to beat about 3 additional minutes. Add your eggs to the butter and sugar mixture, one at a time making sure to beat them in well. Beat in the vanilla and the honey.
• Taking turns, add the dry ingredients and then the buttermilk. Start with ⅓ of the dry ingredients and then add half the buttermilk. Repeat with the dry and then buttermilk and then finish with the last ⅓ of the dry ingredients.

To assemble the whole cake to bake

• Take your sprayed cake pan and smear the four tablespoons of butter MOSTLY on the bottom with a little going up the sides. It will look like too much butter, I know, but this will all turn magical with the plums, the brown sugar and the baking process, so just trust in me.
• After the pan is covered in copious amounts of butter sprinkle the brown sugar on the bottom of the pan. Cover it nice and good. Place your plum slices on the brown sugar butter mixture, and then pour your cake batter on top and gently spread to cover the whole pan. Bake in on a middle rack for about 55 minutes. Check on it after about 50 - do the toothpick check. If this cake is underdone everything will stick and you will be disappointed.
• When your toothpick comes out clean, pull the cake from the oven and let it sit for no more than 10-15 minutes. put a plate on top of the pan and carefully invert the cake onto the pan. Give it a little tap on top and gently pull the pan up. Cool this before cutting and serving.