Preheat oven to 350°F (175°C). Grease a 9x13 inch baking pan or line with parchment paper leaving an overhang on the sides.

In a large mixing bowl, combine the dry cake mix, eggs, and vegetable oil. Mix with a spatula or hand mixer until a thick dough forms.

Fold in 3/4 cup of the Easter M&M's candies and the white chocolate chips until evenly distributed.

Transfer the dough to the prepared baking pan and press into an even layer using a spatula or lightly greased hands.

Top the dough with the remaining 1/4 cup of M&M's and the pastel sprinkles, pressing them lightly into the surface.

Bake for 20 to 25 minutes, or until the edges are lightly golden and the center is set but still soft.

Remove from the oven and place the pan on a wire rack. Allow the bars to cool completely in the pan before lifting out and cutting into 24 squares.