If you love oranges, then you'll love this Orange Upside-Down Cake. A beautiful layer of oranges top this delicious cake flavored with orange zest and fresh thyme. It's a tender cake with a little texture from the cornmeal.
Place the cornmeal and buttermilk in a small bowl and whisk to combine. Allow this mixture to sit for 15 minutes before adding to the other ingredients. This step softens the cornmeal.
For the Orange Topping
Preheat the oven to 350 degrees. Cut the butter into 4 pieces, place them in the 9-inch cake pan and place the pan in the oven. Melt the butter until it just melted - 2 minutes. With a pastry brush, brush the butter up the sides of the pan. Sprinkle the sugar over the butter. Layer the orange slices on top of the sugar, overlapping the oranges in spiral pattern.
For the Cake
Place the flour, salt, baking powder, and baking soda in a medium bowl and whisk until the ingredients are well combined, about 30 seconds.
Place the sugar in a medium bowl. Zest the orange on top of the sugar, until you have what looks like 2 teaspoons. Add the thyme and use your fingers to rub the zest and thyme into the sugar. Place the sugar in the bowl of a stand mixer. Add the butter. Beat the butter and sugar mixture on medium speed until light and fluffy, about 3 to 4 minutes.
Add one egg at a time, beating after each addition. Add half of the flour mixture and mix at low speed until well combined. There may be some flour on the sides of the bowl - that's okay. Add all the buttermilk-cornmeal mixture and mix on low speed until combined. Add the remaining flour and mix on low speed. Scrape the sides and bottom of the bowl and mix for another 10 seconds to ensure all the ingredients are well combined
Gently pour the batter over the orange slices and smooth the top with an offset spatula. Bake until a cake tester comes out clean, about 45 minutes. Let the cake cool in the pan for 10 minutes. Run a knife around the edges to release the cake and invert it onto a platter or plate.
Orange Glaze (Optional)
Make this glaze after the cake has cooled to room temperature.
Combine the orange juice, lemon juice, and sugar in a small saucepan and bring to a boil. Reduce the heat to medium-low and allow it to simmer until it thickens. Stir in the apricot jam and then remove the pan from the heat.
Allow the jam to cool until it is just a little warm and then brush the glaze over the top of the cake,
Serving and Storing the Cake
Serve the cake at room temperature. You can eat the cake as soon as it is cool, but it will taste even better the next day. The cake tastes really good with a dollop of lightly sweetened whipped creme fraiche or whipped cream. Use a sharp knife to cut through the oranges and cake.
The cake can sit a room temperature for 2 days in a covered container and in the refrigerator for 1 week.
Notes
If you don't have Cara Cara oranges use regular navel oranges.If you don't have cornmeal use 1-1/2 cups (192 grams) of flour instead.If the orange peel is thicker than 1/4-inch, then cut it off after slicing the oranges. When the peel is too thick the overall flavor will become bitter.