• In a large bowl with an electric mixer or in the bowl of a stand mixer cream the butter, margarine, brown sugar and granulated sugar with a hand mixer until nice and fluffy.
  
• Add in the egg and vanilla and continue mixing until well incorporated.
  
• Gradually add in the flour, dry pudding mix, baking soda and salt mixing slowly after each addition. Continue until all of the dry ingredients have been incorporated.
  
• Stir in the chocolate chips and mix gently. Add in 1/2 the m&ms and fold in using a rubber spatula.
  
• Cover the bowl with plastic wrap and place the dough in the fridge to chill for 3 hours or overnight.

When you are ready to bake

• Preheat the oven to 350 and line a baking sheet with parchment paper.
• Using a cookie scoop or spoon scoop out the dough about 1 1/2 tablespoons at a time. Roll the dough into a ball and place the balls of dough on the prepared baking sheet about 2 inches apart. The dough should be firm.
  
• Bake cookies for around 10- 12 minutes or until the edges are golden brown.
• Remove from oven and immediately press a few of the additional m&ms into the top of each cookie. Allow to cool on the cookie sheet for a few minutes and then move to a wire rack to cool completely.