Rhubarb and Raspberry Crostata - Chew Nibble Nosh

Ingredients

• For the Crust:
• 1 1/2 cups all-purpose flour
• 1 1/2 tablespoons sugar
• 1/2 teaspoon kosher salt
• 3/4 cup (1 1/2 sticks) chilled unsalted butter, cubed
• 1 large egg
• 1 tablespoon milk
• For the Filling:
• 1/4 cup cornstarch
• 4 cups 1/2-inch-thick slices rhubarb
• 1 (6 ounce) container fresh raspberries
• 1/2 cup sugar
• 1 large egg, beaten
• Raw sugar
• Sweetened whipped cream or vanilla ice cream (for serving)