Stone Fruit Galette Gelson's

Ingredients

• ½ cup hazelnuts, toasted and skinned
• 2 ½ cups all-purpose flour
• 1 Tbsp granulated sugar
• 1 tsp kosher salt
• 2 sticks unsalted butter, diced and chilled
• 5 Tbsp ice cold water, plus more if needed
• ¼ cup packed light brown sugar
• 4 Tbsp unsalted butter
• ¾ tsp vanilla extract
• ¾ lb plums, halved, pitted, and thinly sliced
• ¾ lb peaches, halved, pitted, and thinly sliced
• 1 egg, beaten
• 2 Tbsp granulated sugar