Adjust oven rack to lower-middle position and heat oven to 375 degrees. 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; kneed quickly to form a ball. Place bread on a baking sheet and confidently slit an X on top with a serrated knife. Brush loaf with egg wash. Bake until golden brown, about 45 minutes. Transfer to a wire rack to cool.