Butternut Squash And Caramelized Onion Galette

Ingredients

• 1 1/4 cups all-purpose flour
• 1/4 teaspoon salt
• 8 tablespoons (1 stick) unsalted butter, cut into
• 1/4 cup sour cream
• 2 teaspoons fresh lemon juice
• 1/4 cup ice water
• 1 small butternut squash (about one pound)
• 2 tablespoons olive oil
• 1 to 2 tablespoons butter
• 1 large onion, halved and thinly sliced in half-moons
• 1 teaspoon salt
• pinch of sugar
• 1/4 teaspoon cayenne, or to taste
• 3/4 cup fontina cheese (about 2 1/2 ounces), grated or cut into small bits
• 1 1/2 teaspoons chopped fresh sage leaves