Macadamia Fudge Squares

Position the rack in the middle of the oven. Heat the oven to 375°F. Line a 10 1/2 x 15 1/2 x 1-inch jelly roll pan with aluminum foil and butter the foil.
In a medium bowl, thoroughly whisk together the flour, cinnamon, and salt. Set aside.
In a large bowl set over a pot of barely simmering water, slowly melt the butter and the chocolate. Stir occasionally. Remove from the heat and, using a whisk, blend the brown sugar into the mixture, stirring until melted. Gradually mix in the granulated sugar. Stir in the eggs and the vanilla. Add the dry ingredients, stirring just until combined. Do not overmix.
Spread the batter evenly in the prepared pan, smoothing it with the back of a tablespoon. Sprinkle the surface with the macadamia nuts and press them gently into the batter. Bake for 13 to 15 minutes, or until the top is set and the bar begins to pull away from the sides of the pan. Do not overbake. The squares should remain slightly moist on the inside. (Note: If the batter rises in the pan during baking, prick the bubbles gently with a fork to release the air.) Remove from the oven and let stand until almost cool.
While the bar is cooling, make the glaze. To web the bar, dip a small whisk into the glaze and squiggle it across the pan. If the glaze becomes too thick, thin it with a little very hot water. Let stand until the glaze is set.
Carefully lift the bar from the pan by grasping the foil on both sides and place it on a large cutting board. Pull down the sides of the foil and cut into 2-inch squares using a thin-bladed, sharp knife. Storage: Store in an airtight container, layered between strips of wax paper, for up to 5 days. These cookies may be frozen.