In a medium bowl, sift together the flour, cocoa powder, and baking powder.

In a liquid measuring cup, whisk together the boiling water and instant coffee.

To the bowl of a stand mixer fitted with the whisk, add the eggs, egg yolk, sugar, sesame oil, vanilla, and salt. Beat on medium-high speed until thickened and lightened in color, about 2 minutes. Beat in the sesame paste.

With the mixer on lowest speed, add half of the flour mixture and (immediately) half of the coffee mixture. Mix until just combined. Repeat, mixing until just combined. Scrape the batter into the prepared cake pan.

Transfer the pan to a wire rack and let cool for 10 minutes. Run a small offset spatula around the perimeter to loosen the edges. Invert the cake onto the wire rack. Remove the parchment. Invert again onto another wire rack so it sits right side up. Let cool completely before transferring to a cake plate.

In a medium bowl, add the chocolate.

In a small saucepan, whisk together the heavy cream, sugar, sesame paste, and salt. Heat over medium heat until it just starts to simmer. Don’t let it boil.

Pour the warm cream over the chocolate and let sit for 5 minutes. Whisk in the vanilla. Let the ganache cool for a minute or so. (Basically, you don’t want the ganache to be too liquidy before pouring it over the cake. It should drip off the whisk thick and slow).

Pour the ganache over the cake, right in the center. Spread evenly, coaxing a few thick lazy drips over the sides in a few places. Let gravity do most of the work here. Sprinkle with the toasted sesame seeds.