How to Make It
Preheat oven to 350°F. Coat a nonstick 12-cup Bundt pan with cooking spray. (Alternatively, brush with melted butter, add 2 Tbsp. flour, rotate to evenly coat, and tap out excess.)
Make cake: Sift together flour, baking powder, cinnamon and salt in a medium bowl. In a large bowl, with an electric mixer on medium-high speed, beat butter and sugar until light, about 5 minutes. Reduce speed to medium and beat in eggs, 1 at a time, mixing well after each addition and scraping down sides of bowl as needed. Beat in vanilla. With mixer on low speed, add flour mixture in 3 batches, alternating with milk. Fold in grated apples. Transfer to prepared pan.
Bake until a toothpick inserted into center of cake comes out clean, about 1 hour 10 minutes. Let cool in pan on a wire rack for about 10 minutes, then unmold onto rack set over a clean, rimmed baking sheet.
Make glaze: Combine brown sugar, butter, vanilla, cream and salt in a heavy saucepan. Stir over medium heat until smooth. Increase heat to high and bring to a boil. Remove from heat and stir until syrupy.
While cake is still slightly warm, poke small holes in top with a toothpick or skewer. Pour about 1/2 of glaze over cake, letting it soak in for 1 to 2 minutes, then pour remaining glaze over cake. Scoop up any glaze that has dripped off and spoon over cake again. Allow to cool completely before serving.