In a bowl, whisk together flour and salt; set aside.
In a large bowl, pour in water and dissolve sugar. Sprinkle with yeast and let stand for about 10 minutes or until frothy. Stir in butter.
Gradually stir in flour mixture until ragged dough forms. Turn out onto lightly floured work surface and knead dough for about 4 minutes or until dough is smooth and no longer sticky. Place in clean oiled bowl; cover and let stand for about 1 hour or until doubled in size.
Preheat oven to 425°F (220°C).
Divide dough in half and roll each out into abut 12 inch (30 cm) rounds. Place each on a pizza pan or baking sheet.
In a bowl, beat together mascarpone, cream, salt and pepper. Spread among both pizza rounds. Top each with pear slices, blue cheese and walnuts.
Bake for about 10 minutes or until edge is crisp and cheese is golden. Remove from oven and sprinkle with arugula to serve. Drizzle with balsamic glaze.