Soft M&M Chocolate Chip Cookies

Soft M&M Chocolate Chip Cookies
From Averie Cooks

3/4 cup unsalted butter, softened (1 1/2 sticks)
3/4 cup light brown sugar, packed
1/4 cup granulated sugar
1 large egg
1 teaspoon vanilla extract
2 cups all-purpose flour
1/4 cup instant vanilla pudding mix (not sugar-free and not 'cook & serve'), OR use 2 teaspoons cornstarch in place of pudding mix (that's what I did)
1 teaspoon baking soda
pinch salt, optional and to taste
3/4 cup semi-sweet chocolate chips
3/4 cup milk chocolate M&M's mixed into the dough + about 1/2 cup for placing on top of dough mounds (optional)

In a mixing bowl, combine the butter, sugars, egg, and vanilla, and beat on medium-high speed until creamed and well combined, about 4 minutes. Scrape down the sides of the bowl and add the flour, pudding mix (or cornstarch), baking soda, and optional salt, and beat on low speed until just combined, about 1 minute.  Scrape down the sides of the bowl again, and add the chocolate chips and 3/4 cup M&Ms, and stir by hand until combined. Roll dough into balls and flatten slightly. If desired, press a few M&Ms into the top of each ball. Place balls on a plate, cover with plastic wrap and refrigerate for at least 2 hours.
Place cookies on a greased or lined baking sheet. Bake at 350 for 11 minutes.