Adjust oven rack to lower-middle position and heat oven to 375. Mix flour, sugar, baking powder and salt in a large bowl. Add beer and stir with a fork until just combined. Turn dough onto a floured surface; knead quickly to form a ball. Place bread on a baking sheet and slit an X on top witha serrated or very sharp knife. Brush loaf with egg wash. Bake until golden brown, about 45 minutes. Transfer to a wire rack to cool.