4 packs of cream cheese at room temperature. (8 ounces per pack.) Place cream cheese in mixing bowl.
Add 1 cup of sugar to the cream cheese. Break each of the 4 eggs separately (eggs are also at room temperature) and add one at a time to cheese and sugar mixture.
On a low speed, mix the cheese, eggs, and sugar until well blended.
Sprinkle 1 tablespoon of cornstarch over mixture.
Add 1/3 cup of key lime juice. If key limes are too tart or not available, use regular limes. Lemon juice can be substituted. If you have it, add one tablespoon of lime/lemon sugar. Mix well.
Line a springform pan with wax or parchment paper.
Fill 2/3 of the pan. Bake at 250 degrees for 1 hour. Leave in oven to set. When the center sets, remove from oven and cool in pan. Wrap and refrigerate.
Open pan and remove the circle part. Gently run knife under cake. Place a plate on top of cake and flip. Remove paper from the bottom of the cake. Flip again. Pat the top dry with a paper towel.
Measure 1 cup of brown sugar.
Press the sugar through a strainer onto the top of the cake.
Place cake into broiler and, leaving the door open, watch closely while the sugar begins to melt and bubble 5-7 minutes. Don't let the sugar darken too much - it will be hard and bitter.
The topping will be sweet and crackly and the cake will be moist and tangy. A delicious contrast. Enjoy!! Thanks for viewing. For awesome napkins, please click on http://goo.gl/wRi61C