Blueberry Focaccia

Pulse sugar and lemon zest in food processor until zest is finely ground and incorporated into the sugar. In a large bowl, whisk 1 ⁄3 cup of the lemon sugar, 3 cups of the flour, the yeast and salt until blended. Heat milk in a 2-cup measure in microwave on high 1 1 ⁄2 minutes, or until temperature registers 130 °F on an instant-read thermometer; add to flour mixture with egg and butter. Mix with a rubber spatula until a soft, sticky dough forms; scrape dough onto a floured surface. Using a dough scraper to assist, knead with some of the remaining 1 ⁄2 cup flour to form a smooth and pliable dough, about 2 minutes. Cover the dough with the mixing bowl; let rest 10 minutes. Line a large baking sheet with parchment paper. Divide dough in half. Working with 1 piece of dough at a time, stretch and pat out on parchment into a 12-in. free-form rectangle, about 1 ⁄4 in. thick. Scatter with half the blueberries and half of the remaining lemon sugar. On floured surface, pat out and stretch remaining dough slightly larger than the first piece and place over bottom dough. Press edges together and tuck under the loaf. Cover with a sheet of greased plastic wrap. Place baking sheet in a war Heat oven to 350 °F. With floured fingers, dimple surface of loaf (pierce any bubbling with a knife tip to release air pockets). Scatter top of loaf with remaining blueberries and lemon sugar. Bake 25 to 30 minutes until golden brown. Slide focaccia onto a wire rack and cool slightly. Serve warm.