Rhubarb Upside-Down Cake

There’s something irresistibly charming about a classic upside-down cake, especially when it’s topped with vibrant red rhubarb. This Rhubarb Upside-Down Cake is tender and buttery, with a golden vanilla crumb that’s soft yet sturdy enough to cradle the juicy, slightly tart rhubarb topping.

• 3 cups rhubarb, cut into 1-inch pieces
• 3/4 cup (150g) granulated sugar
• 4 Tbsp (57g) unsalted butter, cut into small cubes

• 1/2 cup (114g) unsalted butter, room temperature
• 1 cup (200g) granulated sugar
• 2 large eggs, room temperature
• 1 tsp vanilla extract
• 1 tsp orange zest , or orange extract
• 1/2 cup sour cream, full-fat or low-fat, not fat-free
• 1¾ cups (218g) all-purpose flour
• 1½ tsp baking powder
• 1/4 tsp salt
• 1/3 cup (80ml) milk, room temperature