Rhubarb Upside-Down Pie with Sour Cream

Ingredients:

• 165 g (12 tbsp) unsalted butter
• 1 and 1/4 cups light brown sugar
• 220 g rhubarb (about 5 stalks, 1 cm thick)
• 1 and 3/4 cups premium flour*
• 3/4 cup granulated sugar
• 1 teaspoon coarse salt
• 0.5 tsp of soda
• A pinch of freshly ground nutmeg
• 2 large eggs
• 1/4 cup sour milk or kefir
• 1/4 cup sour cream
• 1 tsp vanilla extract
• 1 tsp finely grated lemon zest (1 lemon)

Preparation:

1. Preheat oven to 350°F (175°C). Spray the bottom and inside walls of a 9-inch square metal baking pan with cooking spray.
2. In a small saucepan over medium heat, heat 4 tablespoons butter and 3/4 cup brown sugar, stirring frequently, until the butter is melted. Pour into the prepared pan.
3. Cut the rhubarb in half horizontally, from end to end, laying it flat side down. Keeping the top and bottom halves together, cut the stems diagonally into pieces about 5 cm long. You should have about 90 pieces in total. Arrange them in a herringbone pattern on the bottom of the prepared pan, first lining up the tops in a row at a 45-degree angle, then the next row in the opposite direction (the pairs should form a neat V). Lightly press the rhubarb pieces into the sugar mixture to adhere them; set the pan aside.
4. In a medium bowl, combine the flour, granulated sugar, salt, baking soda, nutmeg, and the remaining 1/2 cup brown sugar. Melt the remaining 8 tablespoons butter in a small saucepan, then pour into a large bowl. Add the eggs, buttermilk, sour cream, vanilla, and lemon zest and whisk until smooth. Fold the flour mixture into the egg mixture and knead into a dough.
5. Pour the batter over the rhubarb in the pan and gently spread it with an offset spatula to even it out. Tap the pan lightly on the counter three times to remove any air bubbles.
6. Bake until a toothpick inserted into the center comes out clean and the pie is golden brown, about 40 minutes. Transfer to a wire rack and let cool for 10 minutes (the rhubarb will be too hot to handle right away). Invert the pie pan onto a serving platter. Let cool completely, about 1 hour, before slicing.
   
   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.