2 1/4 cups all-purpose flour, 1 teaspoon baking soda, 1 teaspoon salt, 1 teaspoon ground cinnamon, 1 cup unsalted butter, at room temperature, 1 cup packed brown sugar, 1/2 cup granulated sugar, 2 large eggs, 1 1/2 teaspoons vanilla extract, 1 cup milk chocolate chips, 1 cup semi-sweet chocolate chips
Preheat the oven to 375°F. Put the flour, baking soda, salt, and cinnamon in a mixing bowl. Stir with the wooden spoon until well mixed. Set aside.
Put the butter, brown sugar, and granulated sugar in another mixing bowl. Using the electric mixer set on high speed, beat together until well blended and creamy, about 3 minutes. (You can do this with a wooden spoon, but it will take longer.) Beat in the eggs and vanilla extract. Add the flour mixture and stir with the wooden spoon until blended. Stir in the chocolate chips.
Scoop up a rounded tablespoonful of the dough and drop onto a baking sheet. Repeat until you have used up all the dough. Be sure to leave about 1 inch between the cookies because they spread as they bake.
Using pot holders, put the baking sheets in the oven. Bake until golden brown, about 10 minutes.
Again, using pot holders, remove the baking sheets from the oven. Lift the cookies from the baking sheets with a spatula, and place on cooling racks. Let cool completely.