From dazzling + -ly.

dazzlingly

1. In a dazzling manner.
   • 1908, Lucy Maud Montgomery, chapter 2, in Anne of Green Gables‎:

     Which would you rather be if you had the choice—divinely beautiful or dazzlingly clever or angelically good?"

   • 1941, Henry Miller, The Colossus of Maroussi, London: Secker & Warburg, published 1945, Part One, p. 22:

     The sun was almost at zenith and the glare was dazzlingly intense.

   • 1963, Hermann Hesse, Steppenwolf (1927), translated by Basil Creighton, revised by Walter Sorell, Penguin, 1964, p. 55,

     And these men, for whom life has no repose, live at times in their rare moments of happiness with such strength and indescribable beauty, the spray of their moment's happiness is flung so high and dazzlingly over the wide sea of suffering, that the light of it, spreading its radiance, touches others too with its enchantment.