01 -
Preheat oven to 350°F. Line two large baking sheets with parchment paper.
02 -
Beat softened butter, light brown sugar, and granulated sugar in a large bowl with an electric mixer for 2–3 minutes, until pale and creamy.
03 -
Beat in egg, corn syrup, and vanilla extract until just incorporated.
04 -
Sift in flour, baking soda, and salt. Mix until a soft dough forms. If the dough appears too sticky, add extra flour by the tablespoon until manageable.
05 -
Gently fold in half of the chocolate chips and half of the M&M’s by hand, being careful not to over-mix.
06 -
For regular-sized cookies, use a 1-tablespoon scoop to form 18–20 dough balls. For jumbo cookies, scoop 2 tablespoons for each ball to yield 12 cookies. Space each ball at least 3 inches apart on prepared trays.
07 -
Press additional chocolate chips and M&M’s onto the tops of each dough ball.
08 -
Bake for 11–12 minutes, until edges are golden but centers remain soft and pale. Do not overbake.
09 -
Remove baking sheets from oven and give them a light tap on the counter to help flatten the cookies. Allow cookies to cool on the pan for at least 30 minutes before transferring.