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 salt. Set aside.
In a large bowl, using an electric mixer, cream the softened butter and granulated sugar together until light and fluffy, about 3 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.
Bake for 25 minutes or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and allow it to cool completely in the pan on a wire rack.
Once cooled, crumble the cake into a large bowl until fine crumbs form.
Melt 4 ounces of the white chocolate with the vegetable shortening in a microwave-safe bowl in 30-second intervals, stirring between each, until smooth.
Pour the melted white chocolate over the cake crumbs and mix thoroughly until evenly combined and the mixture holds together when pressed.
Roll the mixture into 1-inch balls and place them on a parchment-lined baking sheet.
Refrigerate the cake balls for at least 30 minutes to firm up.
Melt the remaining 4 ounces of white chocolate in the same manner until smooth.
Dip each chilled cake ball into the melted white chocolate, allowing excess to drip off, then place back on the parchment paper.
Allow the coated truffles to set at room temperature or refrigerate until the chocolate is firm.
Serve and enjoy your vanilla cake truffles!