Things You'll Need:
- 4 large egg whites
- 3/4 c. sugar
- 1/4 tsp. cream of tartar
- 1 tsp. vanilla
- 3/4 lb. unsalted butter (3 sticks)
- 1 tbsp. instant coffee crystals
- 1 1/2 tsp. water
- 2 oz. chopped semisweet chocolate squares
- Groceries
- Stainless Steel Mixing Bowls
- Instant-read Cooking Thermometers
- Mixing bowls
- Hand Mixers
- Skillets
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Step 1
Whisk egg whites, sugar, 2 tbsp. water and cream of tartar in a large, stainless steel bowl.
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Step 2
Set the bowl in a large skillet filled with 1 inch of simmering water. The depth of the water should be as high as the depth of the egg whites in the bowl.
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Step 3
Beat the egg whites at low speed until the mixture registers 140 degrees F on an instant-read thermometer. Do not stop beating at any time while the bowl is in the simmering water.
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Step 4
Beat the mixture at high speed until it just reaches 160 degrees F, about 2 to 4 minutes.
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Step 5
Remove the bowl from the skillet.
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Step 6
Add vanilla and beat at high speed for 3 to 5 more minutes to cool the mixture.
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Step 7
Using another bowl, beat the butter until creamy.
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Step 8
Take a large scoop of the egg white mixture and beat it into the butter until it is well combined. Continue to beat in about half of the egg white mixture in large scoops.
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Step 9
Scrape the remaining egg whites into the mixture and beat until fluffy. Set aside.
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Step 10
Melt semisweet chocolate in the top of a double boiler over boiling water. Let cool to lukewarm. While the chocolate cools, dissolve instant coffee in 1 1/2 tsp. water and stir into frosting mixture.
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Step 11
Stir cooled chocolate into frosting with a rubber spatula. Use frosting immediately.
