Grape Focaccia with Rosemary

3/4 cup hot water
2 tablespoons cold milk
1 1/2 teaspoons sugar

1 1/4 teaspoons active dry yeast

2 cups all-purpose flour

1 teaspoon kosher salt (or half as much table salt)
6 tablespoons olive oil
1 1/2 cups halved Concord, red or black grapes (optionally seeded)
1 teaspoon fresh rosemary needles, chopped

2 tablespoons coarse (or regular) sugar
2 teaspoons coarse sea salt (or a little less than that of kosher salt)

In the bowl of an electric mixer fitted with the paddle attachment, stir together the water, milk, sugar, and yeast. Let the mixture sit until foamy, about 10 minutes. Add the flour, salt and 2 tablespoons of the olive oil to the yeast mixture and mix well on low. Attach the dough hook, raise the speed to medium-low and knead the dough for 8 minutes longer.

Brush a large bowl with a generous amount of olive oil. Scrape dough into the bowl using an oiled rubber spatula, and brush the top with additional oil (or just roll it around in the oil. The dough is profoundly sticky: do not be alarmed!). Cover with plastic wrap (or a bowl cover) and let it rise in a cool place until it doubles in bulk, 1 1/2 to 2 hours.

Press the dough down with an oiled hand and divide it into two balls. Brush a large baking sheet (or two small ones) with olive oil, place the balls of dough on it and brush the top with more oil. Set it aside for 20 minutes, lightly covered with a kitchen towel.

After 20 minutes, dip your fingers in olive oil and press and stretch each ball of dough into a 8 to 9-inch oval shape. It will be dimpled from your fingers. Cover again with the towel and let it rise for another 1 1/4 hours in a cool place.

Preheat the oven to 450°F. Brush tops of dough with remaining olive oil and top the sprinkle grapes, rosemary, sugar, and coarse sea salt evenly over the dough. Bake for 15 minutes, until the crust is golden brown and puffed around edges. Let cool before serving. Serve warm or at room temperature.

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