1. Start with the quinces for the filling. Remove the fluffy stuff from the quinces and clean them with a kitchen towel. Quarter, peel, core, and cut them into small pieces. Add them to a frying pan along with the lemon juice, water, and sugar, and heat up. Let the quince simmer for about 10 minutes – the quince should have softened slightly and the liquid in the pan should have evaporated almost completely. Remove from the heat and allow to cool.

2. Preheat the oven to 350°F (180°C). Line a 9.5 inches (24cm) springform tin* with baking parchment and grease lightly. Set aside.

3. For the streusels, combine the flour, sugar, and cinnamon in a large bowl. Add the butter in small pieces and then rub everything between your fingers until you have different-sized streusel. Add the rolled oats and mix to combine. Place in the fridge until needed.

4. For the batter add the butter and sugar to a large bowl and mix until light and fluffy. Add the egg and mix until well combined. Add sour cream and vanilla extract and mix in. Mix the wholemeal flour with baking powder, cardamom, and salt. Add to the bowl with the wet ingredients and fold in with a rubber spatula until just combined. Transfer the batter to the prepared springform tin and smooth out the top. Distribute the quince pieces and blueberries evenly on top of the batter and sprinkle the streusel all over. Bake the cake for about 55-60 minutes – the streusels should have gotten some color by then. Take out of the oven and let cool down completely. Serve with some whipped cream. Store in an airtight container at room temperature.