Preheat the oven to 375 degrees. Line a baking sheet with parchment paper.
In a large bowl, combine the cream cheese and butter and beat with an electric mixer until smooth, scraping down the sides and bottom of the bowl as needed.
Add the egg, vanilla extract and salt and beat to combine.
Stir in the cake mix and beat until combined, scraping down the bowl as needed.
If using rainbow jimmies, fold in with a spatula.
Shape the dough into 1 inch balls or use a 1 inch ice cream scoop for convenience.
Roll the cookie dough balls into the sprinkles or simply top with extra sprinkles. Place the dough balls on the prepared baking pan, about 1.5 to 2 inches apart.
Bake for 8 to 12 minutes. Remove from the oven and immediately push the chocolate eggs in the middle of the cookie. Carefully place the cookies on a cooling rack. Allow to cool before serving.