Monday, September 26, 2011

Cheesecake - You crack me up!

First, I'd like to apologize to my loyal readers for my lack of posting. I have been busy working on another blog: School of Eating Good, which is my new baby. This blog features recipes, techniques, and information on basic cooking. School of Eating Good is targeted at young adults who find themselves cooking, often for the first time in their lives. On Facebook, School of Eating Good is associated with Boulder, CO Food Revolution, part of the Jamie Oliver Food Revolution. Search for us and like us!

Back to the cheesecake...lots of people ask me about cheesecake. Has to be the most challenging "easy" dessert out there. Why does my cheesecake crack?? How can I stop this? Why is my cheesecake dry and grainy? I offer a few suggestions here and a recipe.

First big problem with cheesecake - you over-bake it. It's not really a cake, it's a custard. If you bake it until it's solid, it's over-baked. It should jiggle in the center when you take it out of the oven. If the recipe says bake until it doesn't jiggle, get a new recipe, like the one below. Baking the cheesecake less will solve both the cracking and the dry, grainy problem.



Second problem - baking at too high a temperature. Custards like a gentle heating. If you bake at too high a temperature, the custard will break. Broken custards are not smooth and creamy. They are dry and grainy (science geeks see Note). Some recipes call for baking the cake in a water bath. I'm not a big fan of this method because if your springform pan leaks, you have a serious mess on your hands. A water bath helps with heat transfer and keeps the outside of the cake from overheating. If you are baking your cheesecake with a crust, like graham crackers, this helps too. I think if you stick to recipes that bake at 300 F, you are in the right place, with or without a water bath. Slow gentle baking is key.

Third problem - your oven. Just because it says 300 F, doesn't make it so. Ovens are not as accurate as you think. Get yourself an oven thermometer and see how close to 300 F it is when you set it to 300. You may be surprised.

Fourth problem - overbeating. Beating introduces air bubbles. Lots of beating introduces more bubbles. Bubbles of air expand when baked. Your cake rises too far too fast, causing cracks, then it falls. This is particularly a problem where I live, at 5400 feet. Everything rises more at the low air pressure here. Once you add the eggs to the batter, don't beat any more than what it takes to incorporate the eggs into the batter. Your cream cheese should be beaten smooth before the eggs go in. If there are still lumps of cream cheese when you add the eggs, you are guaranteed of overbeating in your attempt to smooth it out.

Fifth problem - your cream cheese and eggs are too cold. This is a corollary to problem #4. You are going to have a devil of a time getting the cream cheese smooth if it's not soft and at room temperature. If your eggs are cold, the cream cheese is going to clump up when you add the eggs. Get everything to room temperature before mixing them together.

[Science Geek Note: When proteins are overheated, they unravel and let go of water.  The water gets absorbed into the cake but you are still left with dry bits of protein. Because the cake is no longer homogeneous, you lose the creaminess that makes cheesecake so wonderful. If you have ever overcooked scrambled eggs, you experienced this more obviously - unpleasantly dry curds of egg and water in the pan.]

Mocha Swirl Cheesecake
(from The Weekend Baker by Abigail Johnson Dodge)
Serves 16, one 9" cake

Crust
1 1/2 cups (6 oz) thin chocolate cookie crumbs, such as Famous Chocolate Wafers by Nabisco
3 tablespoons sugar
4 tablespoons unsalted butter, melted

Filling
8 oz. good quality bittersweet chocolate, finely chopped (good brands include Scharffenberger, Valhrona, and Callebaut)
1 tablespoon dark rum or water
1 1/2 teaspoons instant coffee granules (espresso, regular or decaf)
3 8 oz. packages cream cheese (not the lowfat kind either!), at room temperature
1 1/4 cups sugar
1/4 teaspoon salt
1/2 cup sour cream, at room temperature
2 teaspoons vanilla extract
3 large eggs, at room temperature

Position rack in the middle of the oven. Heat oven to 400 F.

In a medium bowl, combine the cookie crumbs and sugar. Stir until well blended. Drizzle the melted butter over the crumbs and mix with a fork until well blended.

Dump the crumbs in a 9" springform pan. Place a piece of plastic wrap over the crumbs. The plastic keeps the crumbs from sticking to your hands. Press the crumbs up the side of the pan to cover about 2". Distribute the remaining crumbs evenly over the bottom. With the bottom of a flat-bottomed measuring cup, press the crumbs firmly into the bottom.

Bake the crust for 10 minutes. Set aside on a wire rack to cool. Once the crust is cool, you can cover it with plastic wrap and set it aside for up to 2 days before filling the crust.

When you are ready to fill the crust, preheat the oven to 300 F. If you are proceeding immediately from baking the crust, reduce the oven temperature to 300 F.

Melt the chocolate in a double boiler. Stir until smooth and set aside. In a medium bowl, combine the rum with the coffee granules and stir. Set aside, stirring occasionally, to dissolve the granules.

In a large bowl, beat the cream cheese with an electric mixer on medium-high speed until very smooth and fluffy. Scrape down the sides of the bowl. Add the sugar and salt and beat until well blended, scraping down the sides to assure even mixing. The batter should have no lumps. Add the sour cream and vanilla and beat again, scraping down the sides once, until well blended. Add one egg at a time and mix until egg is incorpoated. Do not mix the batter more than needed to incorporate the eggs since this can add too much air and lead to cracking of the cake.

Scoop out 2 cups of batter and add to the bowl with the coffee mixture. Stir well to combine.

Add the melted chocolate to the remaining batter in the large bowl and stir well to combine.

Spread 1/3 of the chocolate batter in the springform pan. Add 1/3 of the coffee batter on top of the chocolate batter. No need to spread the coffee batter evenly. Repeat with another 1/3 of chocolate batter, 1/3 coffee batter, the final 1/3 of chocolate batter, and final 1/3 of coffee batter. Stick the handle end of a wooden spoon into the cake and drag the spoon in a few S patterns through the batter to swirl. Lightly bang the pan on the counter a few times to remove any large air bubbles.

Place the springform pan on a rimmed cookie sheet (this makes it easier to get it in and out of the oven) and then place it in the preheated oven. Bake for about an hour. The center of the cake will still jiggle when you remove it from the oven. Do not bake it until it no longer jiggles; this will result in a dry, crumbly, cracked cheesecake. Cool the cake on a wire rack for 15 minutes and then chill for at least 6 hours before serving.

To serve, run a thin metal spatula  around the edge of the pan,  release the clasp and remove the ring. If you are brave, you can run a long metal spatula between the bottom crust and the pan bottom and slide it onto a plate. But, usually, I am not that brave! To cleanly slice the cake, stick a thin bladed knife or cake slicer in a glass of hot water. Slice a piece of the cake, dunk the knife in the hot water, wipe clean and repeat.

Link to PDF of Mocha Swirl Cheesecake

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