Preheat oven @ 350° and place rack in the center position. Butter (or spray with non stick vegetable spray) a 9" round cake pan with 3" sides.
For the topping : Place the butter and brown sugar in a sauce pan and stir over medium heat until butter is melted and sugar has dissolved. Continue cooking without stirring , for a few minutes or until bubbles just start to appear around the outside edges of the mixture (the sugar starts to caramelize). Then remove from heat and pour into your prepared pan. Evenly arrange the fresh pineapple slices on top of the sugar mixture (can also garnish with cherries)
CAKE BATTER : In a large bowl , sift or whisk together the flour , baking powder and salt.
In the bowl of your electric mixer , or with a hand mixer , beat the butter ans sugar until fluffy. Scrape down the sides of the bowl and then beat in the vanilla extract. Add the egg yolks , one at a time , beating well after each addition. Scrap down the sides of the bowl. Add the flour mixture (in three additions) , alternately with the milk (in two additions) ending with the dry ingredients.
In a clean bowl , whisk the egg whites with cream of tartar just until the whites hold a firm peak. With a large spatula gently fold the beaten egg whites into the cake batter in two additions. Pour the batter into the cake pan , smoothing the top.
Bake in preheated oven for 45-55 minutes, or until the top of the cake has browned and starts to pull away from the sides of the pan (a toothpick inserted into the cake NOT THE PINEAPPLE will come out clean.
Remove from oven and place on a wire rack to cool for about 10 minutes. Run a sharp knife around the edge of the pan and then invert the cake onto your serving plate.
Serve with softly whipped cream.
NOTE* Can substitute one -20 oz. can of pineapple slices (drained). Once drained , pat the pineapple slices dry with a paper towel and arrange on top of the sugar mixture. Place a maraschino cherry in the center of each pineapple slice.