Cook the butter over medium heat in a saucepan, stirring frequently. The butter will melt, then bubble, then foam. After the butter browns, set aside to cool slightly.

In a medium bowl, combine the dry ingredients (flour, baking soda, salt, cinnamon).

In the bowl of a stand mixer or in a large bowl using an electric hand mixer, combine the brown butter, brown sugar, granulated sugar, and maple syrup until fully incorporated.

Add the eggs and vanilla and beat on medium speed until the mixture lightens in color and thickens slightly.

Reduce the mixer to low and slowly add the dry ingredients, until just combined. Do not overmix.

Using a rubber spatula or wooden spoon, stir in the hazelnuts and white chocolate chips.

Let the batter sit at room temperature for at least 30 minutes to allow the flour to absorb some of the liquid and for the batter to thicken.

Preheat the oven to 375F.

Use a 1-oz scooper to portion out the cookies on a parchment lined baking sheet. Make sure the cookies are spaced out, as they will spread in the oven. Sprinkle the flaky sea salt on top of the cookie dough balls.

Bake for 9-11 minutes, or until the edges are golden brown but the centers are still soft. Allow to cool completely on a wire rack (or be like me and eat one piping hot out of the oven).