1-First: preheat your oven to 350°F and prepare a 9×9-inch pan by greasing it and lining with parchment paper.

2-Next, whisk together the dry crust ingredients like flour, cocoa powder, and salt in a bowl.

3-Then, cream the softened butter and sugar until light and fluffy, and mix in the egg yolk and vanilla extract before adding the flour mixture to form the dough.

4-Press the dough evenly into the prepared pan and bake for 23 to 25 minutes until it’s set and firm.

5-After baking, let the crust cool completely on a wire rack.

6-For the ganache, heat the heavy cream until it’s steamy, then pour it over the chopped bittersweet chocolate, let it sit for 5 minutes, and whisk until smooth before stirring in the butter.

7-Pour the ganache over the cooled crust and top it with flaky sea salt, mini marshmallows, roasted chopped almonds, and a drizzle of melted dark chocolate if you like.

8-Let the bars set at room temperature for 4 to 6 hours or chill in the refrigerator for 1 to 2 hours.

9-Once set, slice into bars and serve for the best texture and flavor.