Position oven rack in center; preheat oven to 350°; butter a 13 x 9 inch baking pan, line bottom with parchment paper, butter the paper and dust the inside of the pan with flour; tap out the excess flour and put the pan on a baking sheet.
Whisk the flour, baking powder, baking soda, spices, and salt together.
In a saucepan, melt the butter over low heat; add in the brown sugar and stir with a whisk until it is melted and the mixture is smooth, about 1 minute; remove pan from the heat.
Still working in the saucepan, whisk in the eggs one at a time, mixing until they are blended.
Add in the applesauce, vanilla, and applejack; whisk until the ingredients are incorporated and the mixture is once again smooth.
Switch to a rubber spatula and gently stir in the dry ingredients, mixing only until they disappear, then mix in the apple, raisins and nuts.
Scrape the batter into the prepared pan and smooth the top with a rubber spatula.
Bake for 23-25 minutes or until the bars just start to pull away from the sides of the pan and a knife comes out clean.
Transfer the baking pan to a rack and let cake cool while you make the glaze.
In a small saucepan, whisk together the cream, sugar, butter, and corn syrup; put pan over medium heat and bring mixture to a boil, whisking frequently.
Adjust the heat so the glaze simmer, and cook, whisking frequently for 5 minutes; remove pan from heat and stir in vanilla.
Turn the bars out onto a rack, remove the paper and invert the bars onto another rack, so they are right side up.
Slide the parchment paper under the rack to serve as a drip catcher.
Grab a long metal icing spatula and pour the hot glaze over the bars, using the spatula to spread it evenly over the cake.
Let them cool to room temperature before you cut them.
Cut into 32 rectangles, each about 2 ¼ x 1 ½ inches.