Preheat the oven to 170C/Gas3-4; line a square 20cm cake tin with baking parchment
Break the bananas into short chunks, then put them into a bowl and mash roughly with a fork; do not turn them into a puree; stir in the lemon juice
Sift together the flour, baking powder and salt
Break open the cardamom pods, remove the dark brown seeds, then crush them to a fine powder using a pestle and mortar; mix them with the 2 tbsp golden caster sugar and set aside for later
Put the golden caster and muscovado sugar into the bowl of an electric mixer; break the eggs into the sugar, then beat, using the whisk for three to four minutes until light and creamy; pour in the oil, slowly with the mixer on a moderate speed
Fold the flour and baking powder into the mixture; fold in the crushed bananas, briefly, taking care to distribute them evenly but without crushing them any further
Transfer the mixture to the prepared cake tin; sprinkle the surface with the sugar and cardamom mixture; bake in the preheated oven for 35 minutes, or until lightly firm on top, remove from the oven and leave to settle in its tin, for about 20 minutes
Lift the cake from its tin, then place on a rack and leave to cool; cut the cake into three equal rectangles, then cut those into four to give 12 small pieces; serve on their own with a fruit salad
12 servings