1 large egg, at room temperature
1/2 teaspoon vanilla extract
2 cups all-purpose flour
3/4 cup powdered sugar
1/2 teaspoon kosher salt
1/2 teaspoon baking powder
10 tablespoons unsalted butter (1 1/4 sticks), at room temperature and cut into small pieces
Cooking spray, such as Pam
1 cup granulated sugar
3/4 cup heavy cream
1/2 cup light corn syrup
4 tablespoons unsalted butter (1/2 stick)
1/4 teaspoon kosher salt
1/2 teaspoon vanilla extract
1 1/2 pounds milk chocolate couverture or coarsely chopped milk chocolate