Make the Cranberry Sauce:
In a heavy-bottomed saucepan, combine all but ¼ cup of cranberries, ½ cup sugar, orange zest, and lemon juice.
Cook over medium heat, stirring frequently, until cranberries soften and sugar dissolves.
Increase heat to medium-high, cooking until cranberries burst (about 5-6 minutes).
Stir in reserved cranberries, add more sugar if needed, and season with salt and pepper.
Allow to cool before use.
Prepare the Cake Pans and Caramel Glaze:
Grease six 4-inch springform pans and line the bottoms with parchment paper.
In a standing mixer, beat butter, brown sugar, corn syrup, vanilla, and salt until light and fluffy (4-5 minutes).
Divide the glaze between the pans and spread evenly.
Layer with cranberry sauce and top with pineapple rings, pressing gently.
Make the Cake Batter:
Preheat oven to 350°F (175°C).
Separate egg whites and yolks. Beat egg whites until frothy, adding ¼ cup of sugar to form stiff peaks.
In a separate bowl, cream butter, remaining sugar, and brown sugar. Add vanilla, followed by egg yolks.
Whisk together flour, cornstarch, baking powder, and salt.
Alternate adding dry ingredients and buttermilk to the wet mixture, then gently fold in egg whites.
Divide batter into the prepared pans, filling almost to the top.
Bake for 30-35 minutes until a toothpick comes out clean.
Let cakes rest for 5 minutes, then invert them onto plates. Wait before removing the pans and parchment.
Serve warm or store for up to 3 days in the fridge.