Soften the cream cheese: Let the cream cheese sit at room temperature for at least 30 minutes before starting. This prevents lumps when mixing.
Beat until smooth: Using a hand mixer, beat the cream cheese alone for 1-2 minutes until pale and completely smooth, scraping down the bowl once.
Mix in sugar and vanilla: Add the powdered sugar and vanilla extract, mixing until glossy with no visible sugar streaks, about 1 minute.
Fold in whipped topping: Gently fold in the whipped topping with a spatula until fully incorporated and the mixture looks light and airy.
Add green coloring: Add a few drops of green gel food coloring, folding gently until the dip turns an even, soft green shade.
Fold in cake crumbs: Fold in most of the crumbled vanilla cake, reserving a small handful for topping later.
Chill the dip: Cover the bowl and refrigerate for at least 1 hour so the dip firms up enough to hold its shape when scooped.
Transfer to serving dish: Spoon the chilled dip into a shallow serving bowl, smoothing the top with the back of a spoon.
Add toppings: Drizzle the melted white chocolate over the top in thin lines, then scatter the reserved cake crumbs and sprinkles evenly.
Serve with dippers: Serve immediately with graham crackers, vanilla wafers, or fresh strawberries for dipping.
