Preheat the oven to 350°F (175°C). Grease and flour an 8-inch round cake pan.
In a medium bowl, whisk together the all-purpose flour, baking powder, and 1/4 teaspoon salt. Set aside.
In a large bowl, beat the softened butter and granulated sugar together until light and fluffy, about 3-4 minutes.
Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.
Alternately add the flour mixture and whole milk to the butter mixture, beginning and ending with the flour mixture. Mix until just combined.
Pour the batter into the prepared cake pan and smooth the top with a spatula.
Bake for 25 minutes or until a toothpick inserted into the center comes out clean.
Allow the cake to cool completely in the pan on a wire rack.
Once cooled, crumble the cake into a large bowl using your hands or a fork.
In a small saucepan, heat the heavy cream and 1/4 teaspoon salt over medium heat until it just begins to simmer. Remove from heat.
Pour the hot cream over the chopped white chocolate in a heatproof bowl. Let sit for 2 minutes, then stir until smooth to make white chocolate ganache.
Pour the ganache over the crumbled cake and mix thoroughly until fully combined and sticky.
Cover the mixture and refrigerate for 30 minutes to firm up.
Line a baking sheet with parchment paper.
Using a small cookie scoop or tablespoon, scoop out portions of the mixture and roll them into 1-inch balls with your hands.
Place the cake balls on the prepared baking sheet and refrigerate for another 15 minutes.
Optional: Melt additional white chocolate for coating. Dip each chilled cake ball into the melted white chocolate, allowing excess to drip off, then place back on the parchment paper to set.
Refrigerate the coated truffles until firm, about 15 minutes.
Serve chilled or at room temperature.