Preheat the oven to 400 degrees. Line a 18x13 baking sheet with parchment paper. Place all of the saltines salt side up on the baking sheet in an even layer.
Add the brown sugar and butter to a medium sauce pan and bring to a boil over medium heat, stirring occasionally. Boil for 3 minutes.
Carefully pour the boiling mixture over the crackers and put in the oven for five minutes.
Remove from the oven and sprinkle evenly with the chocolate chips. Return to the oven for 1 minute.
Spread the chocolate chips out into an even layer and sprinkle the m&ms over the chocolate.
Let cool on the counter for about 20 minutes. Place in the freezer for 20 more minutes and then cut into small pieces.
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Notes
The chocolate chips will not change shape in the oven. When you remove the pan from the oven, they should spread easily. Do not overbake or the chocolate will burn.