Line the bottom and sides of a 9-inch/22 cm springform pan with parchment paper. In a small saucepan, warm the cream for the ganache over low heat. Add the chopped white chocolate and stir gently until just melted and smooth. Remove from heat and set aside to cool.
In the bowl of a stand mixer fitted with the whisk attachment, whip the heavy cream and vanilla pudding on medium speed until thickened but not fully stiff. With the mixer running, slowly stream in the milk and powdered sugar. Continue beating until the mixture holds soft peaks. Using a spatula, gently fold in the yogurt until fully combined.
Briefly dip each biscuit in milk and line the sides of the prepared pan. Arrange a single layer of dipped biscuits on the bottom.
Spread half of the cream over the biscuit layer and smooth the surface. Top with another layer of dipped biscuits. Spread about two-thirds of the remaining cream on top and smooth again.
Pour the cooled ganache over the cream layer, letting it spread naturally. Transfer the remaining cream to a piping bag and pipe decorative swirls along the edge.
Top with fresh berries, if desired. For added color, drizzle with pistachio butter. Refrigerate for at least 3 hours, or overnight, before unmolding and slicing.