"Estimate the appropriate flour amount for a Christmas cake using these ingredients: 1.38 kg soaked fruits in dark rum, 165 g nuts, 300 g flour, 50 g almond flour, 225 g butter, 125 g dark muscovado sugar, 25 g white sugar, 5–7 g cocoa, 5 eggs, 3/4 medium grated apple, 8–10 g orange zest, 4–5 g lemon zest, 1 tsp vanilla, 180 ml caramel, and 3–4 tbsp fruit-soaked syrup. The user is asking specifically how much flour is needed; provide a metric-based recipe estimate and adjust flour if needed for balance."