Preparation

• Preheat the oven to 350°F. Place crackers in a large zip-top bag and seal well. Pulse in a food processor or use a rolling pin or wine bottle to crush crackers into fine crumbs. Melt 1 stick of butter in a small saucepan over medium-low, stirring occasionally.
• Transfer cracker crumbs to a large bowl. Stir in sugar and then melted butter until the mixture is well combined, matching the consistency of wet sand. Transfer to a 9-inch tart pan with a removable bottom or a 9-inch pie plate. Press the crust into an even layer on the bottom and up the sides of the pan. Bake until lightly golden, about 10 minutes. Remove from the oven and let cool completely, about 45 minutes.
• Meanwhile, make the ganache: In the top of a double boiler, combine chocolate chips and cream, and then cook, stirring constantly, until the chocolate is completely melted and the mixture is glossy, 4 to 5 minutes. Remove the double boiler from the stove and the top saucepan from the water, and then stir in the remaining ½ stick of butter, 1 tablespoon at a time, until fully incorporated. Stir in vanilla and kosher salt and let cool to room temperature, about 30 minutes.
• Pour the cooled ganache into the cooled crust. Refrigerate, uncovered, for at least 2 hours and up to 6 hours, covering after 2 hours. Before serving, sprinkle with flaky sea salt, if desired.