Preheat the oven to 375° F
In an electric mixer fitted with the paddle attachment, beat the butter, brown sugar, and natural sugar on medium-high speed for ~ 3 minutes, or until light and fluffy.
On low speed, add the vanilla, then the eggs, one at a time
Meanwhile, sift the flour, baking soda, and sea salt into a medium bowl.
Mix in the oats.
With the mixer on low, slowly add the flour mixture to the butter-sugar mixture. (Don’t overbeat it) With a rubber spatula, stir in the chopped chocolate and cranberries until the dough is well mixed.
With a 1¾-inch ice cream scoop (or two spoons), scoop round balls of dough onto prepared sheet pans.
Sprinkle lightly with fleur de sel.
Bake for 10 to 12 minutes, until nicely browned.