DOUGH: Combine warm water and sugar in a large bowl. Sprinkle yeast over mixture. Let stand until foamy, about 10 minutes.
Stir in next 7 ingredients. Add 2 1/2 cups flour, stirring to combine. Stir in additional flour a bit at a time to make a soft dough. Knead 10 minutes by hand on a lightly floured surface or 5 minutes in a mixer on low speed.
Place dough in a lightly buttered or oiled large bowl. Cover bowl with plastic wrap amnd let rise until doubled in volume, about 1 hour.
Punch dough down on a lightly floured surface. Knead in cranberries. Shape into a flat round about 8-inches in diameter. Place on a parhment-lined baking sheet. Cover lightly with plastic wrap. Let rise until doubled, about 45 minutes.
Preheat oven to 375°F
TOPPING: Gently brush with melted butter and sprinkle with coarse sugar.
Bake in preheated oven for 40-45 minutes, or until golden. Remove from baking sheet and cool on a wire rack.
If you are not serving right away, wrap focaccia well in foil and freeze in a plastic freezer bag. When ready to serve, defrost on counter,. Place in preheated 375F oven for 8-10 minutes, or until warm.