Chocolate Soufflés:

3 tbs unsalted butter, divided
2 tbs unsweetened cocoa powder
3 oz bittersweet chocolate, chopped
1/2 tsp vanilla extract
4 Large eggs
2 tbs granulated sugar
Pinch salt
Pinch cream of tartar
Raspberry Sauce:
5 oz fresh or thawed frozen raspberries
2 tbs granulated sugar
Powdered sugar, for garnish

Preheat the oven to 375°F. Use 1 tbs of the butter to grease two 8-ounce ramekins. Coat the ramekins with cocoa powder, tapping out the excess.

In a large microwave-safe bowl, microwave the chocolate and remaining 2 tbs of butter in 30-second bursts, stirring between each burst, until melted and smooth. Stir in vanilla and egg yolks, one at a time.

In a clean bowl, use an electric mixer to beat the egg whites, sugar, salt, and cream of tartar just until stiff peaks form. Gently fold the egg white mixture into the chocolate. Spoon into the prepared ramekins. Soufflés can be covered in plastic wrap and refrigerated at this point for up to 1 day.

Bake until puffed and set, about 20 minutes (25 minutes if baking directly from the refrigerator).

Raspberry Sauce:
While the soufflés are baking, purée the raspberries and sugar in the bowl of a food processor, blender, or with an immersion blender, until smooth. Press the mixture through a fine mesh strainer to remove the seeds.

Garnish the chocolate soufflés with powdered sugar and serve immediately with raspberry sauce.