Christmas and Hanukkah M&M Sugar Cookies

Instructions
Preheat the oven to 350° Fahrenheit. Line a large pan with parchment paper or your favorite baking mat.
In a large bowl, cream together the butter and sugar. To do this, mix (I'd recommend using an electric mixer) on medium speed for 1-2 minutes, or until it looks pale, light and fluffy. Then add in one egg, plus the yolk of another egg, and the vanilla extract and mix until combined.
Add the flour, baking soda, and salt to a medium sized bowl and whisk to combine. Then pour into the bowl with your wet ingredients and mix until just combined.
Fold in the M&Ms and scoop dough into balls (I used a medium sized cookie scoop, which is equivalent to about 3 tbsp). Place 5-6 cookies equidistant on your lined baking sheet and bake for 12-14 minutes. While one batch is in the oven, refrigerate the next. They're done when the edges are golden and the centers still look gooey. Let cool for about 10 minutes, then enjoy!