Stabilizing Mascarpone Filling with Gelatin: Prue's Critical Fix

When Prue said the cherry and mascarpone filling that you've got is a bit weak and if you'd had overnight to set it would have been better, she identified a common problem with mascarpone-based frostings. Mascarpone has high moisture content and soft texture - unlike pure butter, it doesn't firm up significantly when chilled. The solution is adding gelatin for structure. Bloom 2 tablespoons gelatin in 1/4 cup cold water for 5 minutes, then heat gently until dissolved and let cool to lukewarm (not hot or it will melt the butter). Add the cooled gelatin to the buttercream after incorporating mascarpone, beating until smooth. The gelatin creates a protein network that stabilizes the filling, preventing it from being weak or collapsing under the weight of cake layers. Critical: Keep mascarpone cold when mixing to prevent graininess, and don't overbeat once it's added. Refrigerate the assembled cake overnight as Prue recommended - this allows gelatin to fully set and flavors to meld. The properly set filling will slice cleanly with the knife dropping through as Paul praised.