• Preheat oven to 350 degrees F. Grease a 6 cup capacity (8 x 4 x 2 ¾ inch) loaf pan generously with softened butter. Dust with flour.
• Zest the orange and measure out 1 tablespoon of zest. Put it in a glass measuring cup, then add enough orange juice (and water, if needed) to make ½ cup. Set aside.
• Sift the cake flour, baking powder and sugar into a stand mixer bowl, then add the salt and whisk until your dry ingredients are evenly blended.
• Spoon tablespoons of shortening and softened butter over the dry mixture. Using the paddle attachment of a stand mixer, stir until fat coats the flour mixture.
• Add the eggs and continue beating with the paddle on low, then stream in the orange juice/zest mixture and vanilla extract.
• Scrape the sides of the bowl and beat on medium speed for 2 minutes until smooth and silky.
• Pour batter into prepared pan and bake for 60 minutes. Let cool on a rack for 15 minutes, then carefully remove from pan and let cool completely.

Blueberry Sauce

• In a small saucepan, combine the frozen blueberries, sugar, and pinch of salt.
• Cook over medium heat until the berries thaw and begin releasing their juices, about 4–5 minutes.
• Stir together the cornstarch and water. Add it to the blueberries while stirring.
• Bring the mixture to a gentle simmer and cook for about 1 minute, just until slightly thickened.
• Remove from the heat and stir in the Grand Marnier and lemon juice. Add cardamom (if using).
• Let cool for 15–20 minutes.