Step 1: Make the Cranberry Sauce

1. In a heavy-bottomed saucepan, combine all but ¼ cup of cranberries, ½ cup sugar, orange zest, and lemon juice.
2. Cook over medium heat, stirring frequently, until the cranberries begin to soften and the sugar dissolves.
3. Increase the heat to medium-high and cook for 5-6 minutes, allowing the cranberries to burst.
4. Stir in the reserved cranberries and adjust sweetness by adding more sugar if needed. Season with a pinch of salt and pepper.
5. Remove from heat and allow the cranberry sauce to cool before using.

Step 2: Prepare the Cake Pans and Caramel Glaze

1. Grease six 4-inch springform pans and line the bottoms with parchment paper.
2. In a standing mixer, beat together the butter, brown sugar, corn syrup, vanilla, and salt until light and fluffy (about 4-5 minutes).
3. Divide the caramel glaze evenly between the prepared pans, spreading it out to cover the bottoms.
4. Layer the cranberry sauce over the glaze, then gently press a pineapple ring into the center of each pan.

Step 3: Make the Cake Batter

1. Preheat your oven to 350°F (175°C).
2. Separate the egg whites from the yolks. In a clean bowl, beat the egg whites until frothy. Gradually add ¼ cup of granulated sugar and continue beating until stiff peaks form.
3. In a separate bowl, cream together the butter, remaining sugar, and brown sugar until fluffy. Add the vanilla extract, then beat in the egg yolks one at a time.
4. In another bowl, whisk together the flour, cornstarch, baking powder, and salt.
5. Alternate adding the dry ingredients and buttermilk to the wet mixture, starting and ending with the dry ingredients. Gently fold in the beaten egg whites until just combined.

Step 4: Assemble and Bake

1. Divide the cake batter evenly among the prepared pans, filling them almost to the top.
2. Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
3. Allow the cakes to cool in the pans for 5 minutes before carefully inverting them onto serving plates. Let the cakes rest for a few minutes before removing the pans and parchment paper.

Step 5: Serve and Enjoy

1. Serve the cakes warm for the best flavor, or store them in the refrigerator for up to 3 days.
2. These mini cakes are perfect as individual desserts and pair wonderfully with a scoop of vanilla ice cream or a dollop of whipped cream.