Preheat the oven to 325°F (175°C). Grease a 9 inch Bundt pan.In a large bowl, beat the sugar, oil, vanilla, and eggs with an electric mixer until light and fluffy.Combine the flour, baking soda, cinnamon and salt; stir into the batter just until blended.Fold in the apples by hand. Pour into the prepared bundt pan.Bake for 55-70 minutes or until an inserted toothpick comes out clean.Allow to cool for about 20 minutes in the pan and then invert on to a wire rack.Heat the butter, heavy cream, and brown sugar in a small saucepan over medium heat.Bring to a boil, stirring to dissolve the sugar, then remove from the heat.Add in vanilla and stir until combined. Let sit 5-10 minutes to thicken.Drizzle over the warm cake.