Rhubarb upside-down cake - Better Homes & Gardens Australia

Ingredients

• Melted butter, to grease
• 2 Tbsp unsalted butter, softened
• 1 bunch (530g) rhubarb,trimmed
• 21⁄2 cups caster sugar
• 2 cups plain flour
• 1⁄2 tsp fine salt
• 1 tsp ground cinnamon
• Extra 275g unsalted butter, softened
• 2 eggs
• 2 tsp baking powder
• Finely grated zest and juice of 1 orange
• 1 cup sour cream
• Crème fraîche, to serve