In each jar, add a layer of shortbread cookies, then a second layer whipped cream, a third layer chocolate sauce, and then add in a layer of M&M candies. Repeat one more time.
Once all jars are filled, store in the refrigerator.
Add decorations, if desired, and serve cold.
Notes
Make this trifle for different holidays or events by using different colors of M&Ms (i.e. green and red for Christmas, black and orange for Halloween, etc.)
Want to make a healthier version of this patriotic trifle? Use fresh strawberries and blueberries instead of candy.
Swap the shortbread for your favorite cookie, graham crackers, or thinly sliced pound cake.