Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or silicone baking mats.

Cream the butter and sugars in a large mixing bowl using an electric mixer on medium speed until light and fluffy (about 2-3 minutes).

Add the eggs and vanilla extract to the butter mixture. Beat until fully combined.

In a separate bowl, whisk together the flour, baking soda, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Fold in the M&M’s and chocolate chips (if using) until evenly distributed.

Scoop tablespoon-sized portions of dough onto the prepared baking sheet, spacing them about 2 inches apart.

Bake for 8-10 minutes, or until the edges are lightly golden and the centers are still soft.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

Serve and enjoy! Store any leftover cookies in an airtight container for up to a week.