Strawberry and Rhubarb Upside-Down Pie

Ingredients:

Pie

• 1 and 3/4 cups all-purpose flour (see Note)
• 1 teaspoon baking powder
• 0.5 tsp of soda
• 0.5 tsp fine salt
• 3/4 cup milk
• 1/4 cup sour cream
• 110 g unsalted butter, room temperature
• 1 cup of sugar
• 2 large eggs
• 1 tsp vanilla extract

Caramel topping

• 1 tbsp unsalted butter, plus extra for greasing the pan
• 0.5 cups of sugar
• 1 1/2 cups rhubarb, trimmed, halved lengthwise and cut into 1cm pieces (about 150g)
• 1.5 cups strawberries, hulled and thinly sliced ​​(about 150 g)
• 1 tbsp cornstarch
• 2 tbsp. strawberry jam

Preparation:

1. Preheat oven to 175°C. Grease just the sides of a 22cm cake tin.
2. Caramel topping:
   
   In a medium saucepan, combine the sugar and 1/3 cup water and heat over medium heat until the sugar dissolves. Cook, without stirring, but gently swirling the pan occasionally, until the mixture turns amber, 6-8 minutes. If necessary, brush any sugar crystals off the sides of the pan with a pastry brush dipped in water. Remove the pan from the heat and whisk in the butter thoroughly (be careful, as the caramel will splatter).
3. Pour the caramel into the prepared cake pan, tilting the pan to cover most of the bottom (be careful: the pan will be very hot from the caramel).
4. In a medium bowl, combine the rhubarb and strawberries with cornstarch, strawberry jam, and a pinch of salt. Spoon over the caramel sauce and spread into an even layer. Set aside.
5. Cake:
   
   In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. In a smaller bowl, combine the milk and sour cream.
   
6. In a large bowl, beat the butter and sugar with a mixer on medium speed until light and fluffy, about 4 minutes. Add the eggs, one at a time, beating after each addition and scraping down the sides of the bowl as needed, then beat in the vanilla extract. Reduce the mixer speed to low and add the flour mixture in 3 additions, alternating with the milk-sour cream mixture. Knead the dough.
7. Pour the batter into the pan over the rhubarb and strawberries and spread it evenly. Bake the cake until golden brown and springs back when lightly pressed, and a toothpick or cake tester inserted into the cake comes out clean, 55 to 60 minutes. Run a knife around the edge of the cake to loosen it from the pan. Let cool in the pan on a wire rack until almost room temperature, about 1 hour.
8. Invert the serving platter over the pie and, holding them together, quickly flip the pie over so that the topping is facing up on the platter. Let cool completely. Slice and serve.
   
   
   Note
   
   When measuring flour, spoon it into a dry measuring cup and remove any excess. Scooping flour directly from the bag with a measuring cup will compact it, resulting in dry baked goods.