Whisk together the flour, cinnamon, salt, baking powder, and baking soda. Set aside.

Using an electric mixer on medium speed, beat the butter, sugar, and brown sugar until light and fluffy. Add the eggs, one at a time, mixing well after each addition. Mix in the vanilla.

Reduce mixer speed to low. Add the flour mixture in three portions, alternating with two portions of milk. Mix just until combined. Stir in the hazelnuts.

Transfer the batter to the prepared pan and spread evenly. Bake 50 to 60 minutes, or until a pick inserted into the center comes out clean.

Cool the cake in the pan for 20 minutes. Then, flip the cake onto a serving plate to continue cooling.

Place the butter in a medium saucepan or skillet. Cook over medium heat until the butter melts and begins to foam.

Continue cooking, stirring occasionally, until brown specks begin to form at the bottom of the pan and the butter has a nutty aroma.

Transfer the butter (including the browned bits) to a mixing bowl. Set aside until the butter has solidified (about an hour).

Add the cream cheese to the cooled brown butter. Using an electric mixer on medium speed, beat the butter and cream cheese until fluffy. Add the confectioners' sugar, and mix thoroughly.

Add about 1/4 cup of milk, and mix well. Add more milk, a small amount at a time, until the glaze is thick but pourable.

Top the cooled cake with the glaze. Sprinkle chopped hazelnuts on top of the glaze if desired.