Prepare the cake batter according to the package directions.
Divide the batter into four separate bowls and tint each with a different pastel food coloring.
Bake the cake in separate layers or a single pan, then let it cool completely.
Once cooled, crumble each color into fine crumbs.
In each jar, layer a spoonful of one color cake crumble, followed by a layer of frosting.
Repeat with alternating colors until the jar is full.
Top with edible Easter grass and jelly beans to resemble a festive Easter basket.
Add sprinkles if desired, and serve immediately or refrigerate until ready to enjoy.