In a medium-size, heavy-bottom saucepan, place the granulated sugar, cream of tartar, cocoa powder, water and heavy whipping cream, and mix to combine well.

Place the saucepan over medium heat, and bring to a simmer.

Reduce the heat to medium-low, and continue cooking until the mixture thickens and reduces by almost one-quarter (4 to 5 minutes). It will first seem thinner as the sugar melts into the liquid, then eventually thicken.

Remove the pan from the heat, add the chocolate, butter and salt, and whisk to combine well.

Transfer to a heat-safe container with a lid, and allow to cool slightly before serving.

Store in the refrigerator, and warm in a water bath on the stovetop or in the microwave before serving.

In a medium-size, heavy-bottom saucepan, place the granulated sugar, cream of tartar and water, and mix to combine well.

Place the saucepan over medium-low heat, and cook until the mixture is beginning to turn amber in color (to ensure that you do not burn the sugar, clip a candy thermometer to the side of the saucepan and remove it from the heat when the sugar mixture reaches 300°F).

Remove the pan from the heat and, whisking constantly, slowly add the cream. The mixture will bubble fiercely.

Keep stirring until the mixture stops bubbling and is smooth.

Add the butter and salt, and whisk to combine well. Return the saucepan to medium-low heat, and bring back to a simmer.

Cook, stirring frequently, until just slightly reduced (about 2 minutes).

Transfer to a heat-safe container with a lid, and allow to cool slightly before serving.

Store in the refrigerator, and warm in a water bath on the stovetop or in the microwave before serving.

In a medium-size, heavy-bottom saucepan, melt the butter over medium heat. Add the brown sugar, and stir until combined.

Stir in the granulated sugar, and cook over medium-low heat until smooth, stirring frequently. The mixture will clump, and eventually melt after about 3 minutes.

Remove the saucepan from the heat and, whisking constantly, add the cream.

The mixture will bubble quite a lot, and the sugar may seize. It will melt again, though. Continue whisking until the bubbling subsides.

Return the saucepan to medium heat and, whisking occasionally, bring to a simmer.

Continue to cook, whisking occasionally, for about 5 minutes or until the mixture is slightly reduced and coats the back of a spoon.

Add the vanilla and salt, and whisk to combine.

Transfer to a heat-safe container with a lid, and allow to cool slightly before serving.

Store in the refrigerator, and warm in a water bath on the stovetop or in the microwave before serving.

In the bowl of your stand mixer fitted with the whisk attachment or a large bowl with a hand mixer, whip the egg whites until they form soft peaks.

In a medium saucepan, place the sugar, water, cream of tartar and salt, and whisk together.

Cook the mixture over medium-high heat until it reaches the softball stage (240°F on an instant read candy thermometer).

Remove the cooked sugar from the heat.

With the mixer on low speed(making sure the sugar mixture doesn’t hit the whisk), pour the sugar mixture carefully down the side of the mixer bowl.

Add the vanilla extract, and increase the mixer speed to high.

Beat on high speed for 5 to 7 minutes, or until thick, white and glossy, and pours off the beaters slowly.

Transfer to a container with a lid, and served immediately.

Store in the refrigerator, and whisk until smooth before serving. After about 2 days, the sugars in the topping will begin to crystallize, affecting texture a bit but not flavor.