Preheat oven to 375℉. Line a baking sheet with parchment paper or a silicone baking mat. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt until combined. Set aside.

Place dark brown sugar and granulated sugar in a large heatproof bowl and set aside. Melt the butter in a saucepan over medium heat. Once it has melted, start whisking constantly. Watch carefully, it can burn easily if you don’t keep an eye on it! The butter will start to bubble and get a little foamy, and develop a golden brown color with a nutty aroma. This can take several minutes, just keep whisking and make sure it doesn’t burn. Once you see the brown bits start to appear, keep cooking for a minute or so until the butter is browned. Remove from heat and pour into the bowl with the sugars and whisk until smooth. Set aside to cool for 10-15 minutes.

Add the eggs and vanilla to the butter/sugar mixture and whisk to combine. Add the dry ingredients and stir until combined. Fold in the chocolate chips, cranberries, and walnuts. It might be easiest to do this with your hands or an electric mixer, since the dough is pretty dense!

Spoon dough onto baking sheet in about 3 tablespoon sized balls and bake for 15-17 minutes until lightly golden on the edges. They will look slightly underbaked, and this is good! Don't overbake them. Let cool for a couple minutes on the cookie sheet, then transfer to a wire rack to cool.