zucchini and ricotta galette

INGREDIENTS

• 1 1/4 cups all-purpose flour, chilled in the freezer for 30 minutes
• 1/4 teaspoon salt
• 8 tablespoons (1 stick) cold unsalted butter, cut into pieces and chill again
• 1/4 cup sour cream
• 2 teaspoons fresh lemon juice
• 1/4 cup ice water
• 1 large or 2 small zucchinis, sliced into 1/4 inch thick rounds
• 1 tablespoon plus 1 teaspoon olive oil
• 1 medium garlic clove, minced (about 1 teaspoon)
• 1/2 cup ricotta cheese
• 1/2 cup (about 1 ounce) grated Parmesan cheese
• 1/4 cup (1 ounce) shredded mozzarella
• 1 tablespoon slivered basil leaves
• 1 egg yolk beaten with 1 teaspoon water