Preheat the oven to 180ºC, fan 160ºC, gas 4. Put the butter and 60g of the brown sugar in a bowl and cream together with a hand-held electric whisk until pale in colour. Whisk in the egg, almonds and flour.
Stir in the apple sauce and 100g of the frozen fruits. Put the Yorkshire puddings on a baking tray, then spoon in the filling. Top with 50g of the remaining fruit and bake in the oven for 25 minutes.
Meanwhile, put the remaining Black Forest fruits and the remaining brown sugar in a pan with the caster sugar and 1 tablespoon water. Place over a medium heat and cook for 2-3 minutes to make a sauce.
Serve 1 pudding per person, each with a spoonful of crème fraîche, a drizzle of the sauce and a light dusting of icing sugar if liked.