Peach Upside Down Cake

I am not a huge fan of skillet based desserts, but my husband made this earlier this week and it was delicious. 

• 4 medium peaches (about 1 1/2 pounds/680 grams), unpeeled and cut into 1/3-inch-thick wedges
• Juice of 1 lemon
• 1 cup/130 grams cake flour, not self-rising
• ¾ teaspoon baking powder
• ¼ teaspoon baking soda
• 1 cup/200 grams granulated sugar
• 5 ounces/140 grams unsalted butter
• 1 teaspoon pure vanilla extract
• 2 large eggs
• ½ cup sour cream

For the bourbon whipped cream (optional):

• ½ cup heavy cream
• 1 tablespoon bourbon 
• 1/2 tsp. vanilla extract
• confectionery sugar to taste 

1. Heat oven to 350 degrees. Line a rimmed baking sheet with a nonstick baking mat or parchment paper. (This is in case the cake bubbles over during baking.)
2. In a large bowl, toss the peaches with the lemon juice. In a separate bowl, whisk together the flour, baking powder and baking soda.
3. In a 10-inch cast-iron skillet, cook 1/4 cup of the granulated sugar over medium heat, stirring occasionally with a wooden spoon, until the sugar melts and turns a deep amber color, about 10 minutes. Remove from the heat and immediately add 2 tablespoons of the butter, stirring vigorously. The mixture may appear curdled and broken; don’t worry, it will smooth out. Arrange the peach wedges in concentric circles over the sugar mixture, overlapping as needed to make them fit.
4. In a stand mixer fitted with the paddle attachment, beat the remaining sugar, butter and the vanilla bean seeds (or vanilla extract) on medium speed until smooth. Add the eggs one at a time, beating until blended after each addition. Add the sour cream and beat until blended. With the mixer running on low speed, gradually add the flour mixture, beating just until blended and stopping to scrape bowl as needed. Spoon the batter over the peaches in the skillet and spread to cover.
5. Place the skillet on the prepared baking sheet. Bake until golden brown and a tester inserted into the center of the cake comes out clean, 40 to 45 minutes.
6. Make the whipped cream, if desired: In a large bowl, preferably metal, combine cream and bourbon. Refrigerate, along with a metal whisk or mixer attachments, for at least 15 minutes. Once chilled, whip the mixture until it holds soft peaks, 3 to 5 minutes.
7. Let the cake cool in the skillet on a wire rack for 10 minutes. Run a knife around the edge to loosen. If you see liquid around the edges of the skillet, carefully pour off into a measuring cup and set aside. (It’s O.K. if you don’t have any excess liquid — it all depends on how juicy your fruit is.)
8. Carefully invert the cake onto a serving plate and drizzle with any reserved liquid. Let cool about 10 minutes more, to set. Cut into wedges using a serrated knife and serve, topping each slice with whipped cream if you like.