With a rubber spatula, scrape batter into prepared pan and smooth the top. Bake in preheated oven until golden brown around the edges and firm to the touch in the center, about 25 minutes. (Do not bake over 25 minutes or the brownie bars will be too dry.) Transfer to wire rack and allow the brownie cake to cool at least 1 hour before removing from pan. Cool completely before spreading on glaze.