Preheat the oven to 350 degrees. Coat a 9 inch round pan with cooking spray.
Arrange the pear slices in the pan.
Put the butter, eggs, milk, salt, granulated sugar, flour and vanilla into a blender; process until smooth.
Pour the batter over the pears. Bake for 40-45 minutes until the custard is golden and firm to the touch. Dust the top with powdered sugar before serving.
