S’mores Lava Cakes

1 stick unsalted butter, plus more for greasing
1/4 c. sugar, plus more for coating
1 Tbsp. flour
4 oz. bittersweet chocolate, chopped
2 large eggs plus 2 large yolks, room temperature
3 Tbsp. heavy cream
1 graham cracker sheet (2 sqs), finely chopped
2/3 c. marshmallow cream

Grease 4 (6 ounce) custard cups, then coat with sugar; place on baking sheet. In medium bowl, microwave butter and chocolate at medium power for two minutes; stir until smooth. In medium bowl whisk together eggs, yolks and sugar until foamy. Whisk in chocolate mixture, then flour. Fill custard cups 2/3 full with batter. Bake in preheated 425° oven until edges are puffy, 13-15 minutes. Meanwhile in medium bowl microwave heavy cream at high power for 30 seconds. Stir in marshmallow cream until smooth. Carefully invert cakes onto plates and drizzle marshmallow sauce on the side. Top with graham cracker crumbs. (or, if short on time, skip the marshmallow sauce and crumbs and top with your favorite ice cream.)