Whisk the flour, cinnamon, baking soda, and salt together in a medium bowl. Set aside
In a large bowl using a hand mixer or a stand mixer fitted with a paddle attachment, beat the butter, brown sugar, and granulated sugar together on medium speed until combined and creamy. Add the eggs, molasses and vanilla and beat on high speed until combined. Scrape down the sides of the bowl and beat again as needed to combine.
Add the dry ingredients to the wet ingredients and mix on low until combined. With the mixer running on low speed, mix in the the oats, butterscotch morsels and white chocolate morsels until dough is thick and a little sticky. Cover and chill the dough for at least 45 minutes in the refrigerator (and up to 4 days). if chilling for longer than a few hours, allow to sit at room temperature for at least 30 minutes before baking because the dough will be quite hard.
Preheat oven to 350ºF.
Scoop cookie dough onto a baking sheet, about 3 tablespoons of dough per cookie, and place 4 inches apart on the baking sheets. I like to press a few butterscotch morsels into the tops! Bake for 13-14 minutes or until lightly browned on the sides. The centers will look very soft.
Remove from the oven and allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cook completely.
Cookies stay fresh covered at room temperature for up to 1 week.