Melt butter in a skillet over medium heat; continue cooking, stirring occasionally, until golden brown, about 6 to 8 minutes.

Remove pan from heat and scrape butter - and any golden bits - into a medium sized, heatproof bowl. Place bowl in the fridge until butter has come back to room temperature, about 1 hour and 30 minutes.

You'll know it's ready when the butter is solid but just soft enough that you can scrape it out of the bowl (use a strong metal spoon).

Preheat oven to 375 degrees (F). Line a large baking sheet with parchment paper.

In a large bowl, combine flour, salt, cinnamon, and baking soda; whisk well to combine then set aside until needed.

In the bowl of a stand mixer fitted with the paddle attachment or in a large bowl using a handheld electric mixer, combine the chilled brown butter and both sugars; beat on medium speed until light and fluffy, about 2 minutes. Add in vanilla. Beat in egg and egg yolk, one at a time, beating until just combined, and scraping down the sides of the bowl as needed.

Using a rubber spatula, fold in the flour, stirring until just combined. Fold in the chocolate, cranberries, and walnuts.

Scoop 3 tablespoon sized rounds of dough onto the prepared sheet, leaving 2 inches in between each cookie for spreading. Bake for 10 to 11 minutes, or until edges are set and the center is still a little jiggly.

Remove cookies from oven and sprinkle with sea salt, if using.

Allow cookies to cool on the pan for 10 minutes, then carefully transfer to a cooling rack. Repeat with remaining cookie dough.