Rhubarb Blueberry Upside-Down Cake

Ingredients (16)

• 1 1/4 cups unsalted butter
• 3 cups cubed rhubarb
• 3/4 cup blueberries
• 2 tsp. cornstarch
• 1 ½ cups granulated sugar
• ½ cup dark brown sugar
• 2 cups flour
• 1 teaspoons baking powder
• 1/2 tsp. baking soda
• ½ teaspoon fine sea salt
• Zest of 1 large orange
• 1 teaspoon vanilla extract
• 1 tsp. almond extract
• 4 large eggs
• ⅓ cup sour cream
• 2 tsp. orange juice