If using measuring cups, measure 3 cups of flour (weighing is more accurate).
In a standing mixer, beat together butter and sugars until creamy. Scrape down bowl. Crack eggs separately into a separate bowl and add eggs and vanilla to butter/sugar mix. Mix at medium speed until combined but don't overbeat.
Combine flour, soda, cinnamon and salt (best to whiz them together in a food processor for 5-6 pulses). Add flour mixture to creamed mixture while slowly mixing. Mix until combined but not overly beaten. Add cranberries; add oats. At this point you might need to hand stir the mix.
Using tablespoons, form drops of dough slightly smaller than ping-pong balls and place close together on a parchment lined cookie sheet. Freeze the balls for at least an hour. At this point, you can transfer them to a resealable plastic bag and hold in the freezer for a month (if they last that long).
To bake, preheat oven to 350 degrees Fahrenheit. Place cookies on parchment lined baking sheet about 1 1/2 inches apart. Bake for approximately 14 minutes until golden brown. Slide cookies on parchment paper onto a cooling rack. Makes about 8 dozen cookies.