In a large mixing bowl, combine the margarine, salted butter, brown sugar, and granulated sugar. Cream together until light and fluffy. Add the eggs to the mixture one at a time, ensuring each egg is fully incorporated before adding the next. Then add in the vanilla extract and light corn syrup and mix until well combined.

In a separate bowl, sift together the flour, baking soda, and salt. Gradually add this mixture to the wet ingredients, mixing until a dough forms. Fold in the milk chocolate chunks until evenly spread throughout the dough.

Cover and chill the dough in the refrigerator for at least 30 minutes, or up to overnight. This will allow the flavors to develop and make it easier to shape the cookies.

Preheat your oven to 375°F and line a baking sheet with parchment paper.

Using a cookie scoop or spoon, form the chilled dough into small balls and place them on the prepared baking sheet, leaving about 2 inches of space between each cookie.

Bake for 10-12 minutes, or until lightly golden brown around the edges. Allow to cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.

Serve your Insomnia Cookies with a glass of milk or your favorite hot beverage.