In a small pot, brown the butter. Bring the pot to medium-low heat. Stir the butter for 7-10 minutes, until the milk solids start turning brown, and remove from the pot. Don't let it turn black. Allow the butter to cool for 5 minutes
Combine flour, baking powder, salt, and cornstarch. Set aside.
Combine butter, brown sugar, and white sugar. Then add eggs, vanilla extract, almond extract, and molasses.
Mix in the dry ingredients until well combined with the wet ingredients. Fold in the nuts and white chocolate. Roll into balls and place on a baking sheet in the refrigerator for 24-72 hours.
Preheat oven to 350°. Bake cookies for 13-15 minutes. Top with flaky sea salt.
Notes
Choose a light-colored pot. I always try to pick a lighter-colored pot when browning butter so it's easier to see when the butter turns brown.
Refrigerate the dough. This will prevent them from spreading out and will make them chewy and fudgy. We do this for a lot of our cookies!
Combine wet ingredients. Combine them really well so that the sugar crystals are no longer visible. This will make it much easier to combine with the dry ingredients.