I've made this coffee and walnut cake
www.bbcgoodfood.com/recipes/2528636/coffee-and-walnut-cake
Cake tastes delicious and was easy to make but I was confused by the filling. Tried 2 different ways. Followed the recipe and it curdled. Tried one of the other commenters instructions and tried whipping cream first. This looks really nice a glossy but quite thin and I fear may just spill off the cake. I've put it in the fridge to see if it firms and will only fill cake just prior to serving. What am I doing wrong?
Pictures of the 2 different fillings attached!