Defrost the blueberries. Preheat oven (electric cooker: 150 °C/circulating air: 130 °C/gas: see manufacturer). Line a baking tray with baking paper. Mix muesli, nuts, honey, oil and gingerbread spices thoroughly. Spread on the baking tray. Bake in a hot oven for about 25 minutes until golden brown, mixing 2-3 times. Let it cool down.
Stir the quark with vanilla sugar until smooth. Whip the cream until stiff and fold into the quark.
Christmas muesli possibly loosen up a little and take off about 200 g for the trifle. Alternate with vanilla curd, caramel spread and berries in six glasses (each containing approx. 300 ml). Fill the rest of the muesli into a large glass with a lid, close it and use it for other purposes.