For the Ramekins:

1. Preheat the oven to 400°F.
2. Using 1 tablespoon of butter, grease the sides and bottoms of 4 individual 6-ounce ramekins. 
3. Place the 2 tablespoons sugar in one ramekin. Turn the ramekin to lightly coat the greased surface. Pour out the remaining sugar into another ramekin, and turn to coat.
4. Repeat with the remaining ramekins, disposing of any excess sugar. Set aside the prepped ramekins as you prepare the soufflé mixture/base.

For the Soufflés:

1. Completely melt the chocolate and butter together in the microwave, or using a double boiler while stirring continually over low heat. Set aside to cool for 5 minutes.
2. In a large bowl, whisk together the egg yolks, vanilla, and salt until combined. Gradually add the melted chocolate to the yolk mixture, whisking constantly until completely incorporated. Set aside.
3. Using a stand mixer fitted with the whisk attachment, whisk the egg whites and cream of tartar at high speed until they are frothy. Continue whisking at high speed while gradually adding the 3 tablespoons sugar. Whip until the mixture holds glossy, medium-stiff peaks, about 5 minutes.
4. In three separate increments, fold the egg whites gently into the chocolate mixture until completely incorporated and no streaks of egg whites remain.
5. Chill the mixture uncovered in the refrigerator for about 5 minutes, until the mixture has thickened slightly.
6. Divide the mixture among the prepared ramekins. The mixture should reach the top of the rim. Use a small knife or offset spatula to smooth the top of the souffle to make a flat surface.
7. Run a knife around the very top of each soufflé, creating a narrow clearance between the top of the batter and the rim of each ramekin. 
8. Place the ramekins on a half baking sheet and transfer to the oven. Bake until the soufflés have risen above the rims of the ramekins and the tops are dry and the souffles wiggle slightly when you very gently shake the pan, about 12-15 minutes. Avoid opening the oven door excessively, as this may cause the soufflés to collapse.
9. Remove from the oven, dust the tops with powdered sugar, and serve immediately. They will be hot and will deflate quickly!