For the cold brew syrup, whisk together the sugar, cold brew coffee, and vanilla extract until the sugar dissolves. Alternatively, you can combine them all in a mason jar, screw on the lid, and shake it until the sugar dissolves. Cover and refrigerate. Will keep in the refrigerator for up to 2 weeks.

For the molten fudge cakes, sift together the flour and cocoa powder in a small bowl. Set it aside.

Preheat the oven to 450 degrees Fahrenheit. Grease 4 (6-ounce) ramekins and lightly flour them. Set them aside on a baking sheet.

In the top of a double boiler, melt together the butter and the chocolate over low heat until smooth, stirring constantly. Remove from heat and set aside.

In the bowl of an electric stand mixer fitted with the whisk attachment, beat together the eggs, egg yolks, granulated sugar, salt, and vanilla at medium high speed until the mixture thickens and becomes pale and silky, about 3 to 5 minutes.

Remove the bowl from the stand mixer, and fold in the flour mixture and melted chocolate mixture in 4 increments, alternating between adding the two, until incorporated and a smooth batter forms.

Evenly distribute the batter between the prepared ramekins and place the baking sheet in the oven. Bake until the sides of the cakes puff up but the center is slightly jiggly, about 10 to 12 minutes. Remove the tray from the oven and allow the cakes to sit at room temperature for 1 minute, then cover each one with an inverted dessert plate and allow to rest for 20 seconds before flipping it over and unmolding the cake onto the plate. Drizzle with the desired amount of cold brew syrup and serve immediately.