Preheat the oven to 350 F (180 C) and position the rack in the center.
Butter a 9″x 13″ (23cm x 33cm) baking dish and place it on a baking sheet.

Oat topping:
Combine the flour, baking soda, salt, and cinnamon. Set aside.
Beat the butter at medium speed until it’s soft and creamy.
Add the brown sugar and beat for 2 minutes, then add the eggs one at a time, beating well between each addition, then add the vanilla and mix.
The mixture should be light and fluffy.
Reduce the mixer speed and add the dry ingredients, mixing just until they disappear.
Still at low speed, add the oat flakes and peanuts.
Press half of the mixture (reserving the other half) into the prepared baking dish, pressing down with your fingers.

Chocolate topping:
In the bowl of a double boiler, pour the sweetened condensed milk, chocolate chips, butter, and salt, stirring occasionally until the mixture is melted and smooth.
Remove the bowl from the double boiler and add the vanilla, dried cranberries, and peanuts.

Pour the hot chocolate mixture over the oat crust, then spread the remaining oat mixture over the top.
Bake for 25 to 30 minutes until the topping is golden brown.
Transfer the dish to a rack and let cool for 2 hours.
Refrigerate for 1 hour before cutting into squares.