• For the Mushrooms:
• 6 tablespoons unsalted butter
• 2 tablespoon finely chopped garlic
• 1 1/2 teaspoon sea salt
• 1/4 teaspoon black pepper
• 1 lb small white mushrooms
• 2 tablespoons finely chopped fresh flat-leaf parsley
• For the focaccia dough:
• 3 1/2 cups unbleached, all-purpose flour
• 1 1/2 cup water
• 2 teaspoons salt
• 1 envelope active dry yeast
• ¼ cup olive oil
• 6 tablespoons olive oil, divided
• 1 11-x-17-inch jelly roll pan

Directions

1. To make the mushroom:
2. Put oven rack in middle position and preheat oven to 375°F. Melt butter with garlic, salt, and pepper (on the stove or in a microwave). Put mushrooms in an 8-inch square baking dish and toss with garlic butter. Bake, stirring occasionally, until mushrooms are soft and juicy, 15 to 20 minutes. Let it cool.
3. To make the basic focaccia dough:
4. Warm 1/3 cup of water to 110 F. Dissolve the dry yeast into the water and let it rest for 5 minutes.
5. Add the rest of the water and the flour, and mix until the dough come together.
6. Add salt and 3 tablespoon oil and continue kneading until the dough becomes elastic (approximately 15 minutes). Put the dough into a lightly oiled bowl, cover with plastic wrap and allow to rest until it doubles it size (approximately 2 hours).
7. Oil the jelly roll pan with oil. Scrape the dough out of the bowl and onto the pan and pat and press the dough into the pan to fill it completely. If the dough resists, wait a few minutes and continue. With a fingertip, make impressions in the dough at 2-inch intervals. Drizzle dough with the remaining oil. Sprinkle with the Kosher or coarse salt.
8. Arrange mushrooms over the top of the dough covering completely. Drizzle olive oil on the top. Cover the dough with a piece of oiled plastic wrap (oiled side down) and allow the dough to rise again until doubled in bulk, about 45 minutes. Meanwhile, preheat oven to 450 degrees and set a rack in the lower third. When dough has risen, bake until deep golden, about 25 minutes. Check the bottom about halfway through the baking time by lifting the side of the focaccia with a spatula or pancake turner. If it is coloring deeply, slide pan onto another pan to insulate bottom. Spread the parsley on top. Slide the focaccia off the pan onto a rack to cool. Serve warm or at room temperature in narrow slices.